ChemWiki - User contributions [en]

CCL:lydia

2018-05-18T15:54:18Z

Xx516: /* Isomers and point group */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|600px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

[[File:Xx isomer al2cl4br2.jpg]]

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

Relative energy = E(isomer 1)-E(isomer 2) = -2352.406au + 2352.416au = 0.010au = 6.275kJmol-1
The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

== References ==

<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

File:Xx isomer al2cl4br2.jpg

2018-05-18T15:54:06Z

Xx516:

CCL:lydia

2018-05-17T14:14:18Z

Xx516: /* Energies of the two isomers */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|600px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

Relative energy = E(isomer 1)-E(isomer 2) = -2352.406au + 2352.416au = 0.010au = 6.275kJmol-1
The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

== References ==

<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

CCL:lydia

2018-05-17T13:59:11Z

Xx516: /* Vibrational spectrum of BH3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|600px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

== References ==

<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

CCL:lydia

2018-05-17T13:49:49Z

Xx516: /* References */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

== References ==

<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

CCL:lydia

2018-05-17T13:49:38Z

Xx516: /* MOs of the lowest energy conformer */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

== References ==

1. <references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

CCL:lydia

2018-05-17T13:49:06Z

Xx516: /* BH3 MO diagram */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" /> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

CCL:lydia

2018-05-17T13:47:54Z

Xx516: /* BH3 MO diagram */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram <ref name="BH3 MO diagram" />
<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references> with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

CCL:lydia

2018-05-17T13:47:27Z

Xx516: /* BH3 MO diagram */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The quick brown fox jumps over the lazy dog.<ref name="BH3 MO diagram" />
<references>
<ref name="BH3 MO diagram">Patricia Hunt, HuntResearchGroup, http://www.huntresearchgroup.org.uk/teaching/teaching_comp_lab_year2a/Tut_MO_diagram_BH3.pdf, Accessed 16/05/2018 </ref>
</references>

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

CCL:lydia

2018-05-17T13:36:16Z

Xx516: /* MOs of the lowest energy conformer */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

==== The first occupied MO of overall bonding interactions ====

[[File:MO 67.jpg]]

==== The second occupied MO of overall bonding interactions ====

[[File:MO 70.jpg]]

==== The third occupied MO of overall anti-bonding interactions ====

[[File:MO 78.jpg]]

CCL:lydia

2018-05-17T13:34:36Z

Xx516: /* MOs of the lowest energy conformer */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

Below are the bonding and antibonding analysis on three MOS of the isomer with Cl as the bridging atoms and the Br atoms in trans positions.

[[File:MO 67.jpg]]

[[File:MO 70.jpg]]

[[File:MO 78.jpg]]

File:MO 78.jpg

2018-05-17T13:34:30Z

Xx516: Xx516 uploaded a new version of File:MO 78.jpg

File:MO 70.jpg

2018-05-17T13:33:56Z

Xx516: Xx516 uploaded a new version of File:MO 70.jpg

File:MO 67.jpg

2018-05-17T13:32:32Z

Xx516: Xx516 uploaded a new version of File:MO 67.jpg

CCL:lydia

2018-05-17T13:31:56Z

Xx516: /* Frequency optimisation of AlCl2Br */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

Frequency File: [[File:XX ALCL2BR FREQ.LOG]]

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:31:22Z

Xx516: /* Frequency optimisation of Al2Cl4Br2 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency File: [[File:XX AL2CL4BR2 2 FREQ.LOG]]

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:30:17Z

Xx516: /* Frequency optimisation of Al2Cl4Br2 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

Frequency log file: [[File:XX AL2CL4BR2 1 FREQ.LOG]]

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:29:45Z

Xx516: /* Frequency optimisation of BBr3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File: [[File:XX BBR3 FREQ.LOG]]

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:29:23Z

Xx516: /* Frequency optimisation of NH3BH3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

Frequency File: [[File:XX NH3BH3 FREQ.LOG]]

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:28:52Z

Xx516: /* Frequency optimisation of NH3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File: [[File:XX NH3 FREQ.LOG]]

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T13:28:08Z

Xx516: /* BH3 frequency */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File: [[File:XX BH3 FREQ.LOG]]

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

File:XX BH3 FREQ.LOG

2018-05-17T13:25:51Z

Xx516: Xx516 uploaded a new version of File:XX BH3 FREQ.LOG

CCL:lydia

2018-05-17T11:12:16Z

Xx516: /* Frequency optimisation of Al2Cl4Br2 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 1 freqtable.jpg]]

The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T11:11:58Z

Xx516: /* Frequency optimisation of Al2Cl4Br2 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-17T11:06:12Z

Xx516: /* Frequency optimisation of AlCl2Br */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

http://dx.doi.org/10.14469/ch/198289

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T15:37:49Z

Xx516: /* Summary table */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx-nh3bh3 sum1.PNG]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

File:Xx-nh3bh3 sum1.PNG

2018-05-15T15:37:29Z

Xx516:

CCL:lydia

2018-05-15T15:26:49Z

Xx516: /* Energy comparision of the two isomers */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -1176.190au || -7.38*105kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= 1.41*10-3kJmol-1kJmol-1

the product is much more unstable than the divalent metal complex since the Al atom in the monomer is largely electron deficient and it experience no electron donation from the bridging atom.

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T15:20:14Z

Xx516: /* Summary table */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt1 sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -3734.748au || -2.343554*106kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= -3.21*106kJmol-1kJmol-1

=== MOs of the lowest energy conformer ===

File:Xx alcl2br opt1 sum.jpg

2018-05-15T15:20:01Z

Xx516:

CCL:lydia

2018-05-15T15:07:12Z

Xx516: /* Energy comparision of the two isomers */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== AlCl2Br ===

==== Basis set and Calculation method ====
Optimisation of the AlCl2Br molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx alcl2br opt sum.jpg]]

==== Item table ====
[[File:Xx alcl2br opt item.jpg]]

==== Frequency optimisation of AlCl2Br ====

[[File:Xx alcl2br freq table.jpg]]

The convergence of the low frequency values are within the +/-15 region, thus the optimisation is complete.

<jmol><jmolApplet>
<title>AlCl2Br molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX ALCL2BR FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

==== Energies of the two isomers ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 1 || -2352.406au || -1.476134*106kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|}

The energy of isomer 2 is slightly lower than the energy of isomer 1. Isomer 2 uses Chloride atom as the bridging atom. the Cl and Al are in the same period in the periodic table, thus their sizes matches more than Br and Al. Therefore, the orbital overlap of Cl and Al is larger, giving rise to lower energy of the isomer.

==== Dissociation energy for the lowest energy conformer into 2AlCl2Br ====

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| isomer 2 || -2352.416au || -1.476141*106kJmol-1
|-
| AlCl2Br || -3734.748au || -2.343554*106kJmol-1
|}

ΔE=2E(AlCl2Br)-E(Al2Cl4Br2)= -3.21*106kJmol-1kJmol-1

=== MOs of the lowest energy conformer ===

File:XX ALCL2BR FREQ.LOG

2018-05-15T14:34:46Z

Xx516:

File:Xx alcl2br freq table.jpg

2018-05-15T14:33:05Z

Xx516:

File:Xx alcl2br opt item.jpg

2018-05-15T14:32:41Z

Xx516:

File:Xx alcl2br opt sum.jpg

2018-05-15T14:32:14Z

Xx516:

CCL:lydia

2018-05-15T14:23:45Z

Xx516: /* Association Energy */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T14:23:14Z

Xx516: /* Vibrational spectrum of BH3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T14:22:52Z

Xx516: /* Vibrational spectrum of NH3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T14:22:24Z

Xx516: /* Vibrational spectrum of BBr3 molecule */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ Vibration Modes
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

CCL:lydia

2018-05-15T14:20:51Z

Xx516: /* Isomer 2 with Cl as bridging molecules */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 2 freq table.PNG]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>isomer 2 with Cl as bridging molecule and Br trans</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 2 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

File:XX AL2CL4BR2 2 FREQ.LOG

2018-05-15T14:20:11Z

Xx516:

File:Xx al2cl4br2 2 freq table.PNG

2018-05-15T14:19:28Z

Xx516:

File:Xx al2cl4br2 2 opt item.jpg

2018-05-15T14:17:45Z

Xx516:

File:Xx al2cl4br2 2 opt sum.jpg

2018-05-15T14:17:24Z

Xx516:

CCL:lydia

2018-05-15T14:13:12Z

Xx516: /* Isomer 1 with Br as bridging molecules */

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of GEN and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 1 sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 1 opt item.PNG]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx al2cl4br2 1 freqtable.jpg]]
The convergence of the low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>Isomer 1 with Br as bridging molecules</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX AL2CL4BR2 1 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx nh3 freq table.jpg]]
The convergence of the low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>bezene molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===

File:XX AL2CL4BR2 1 FREQ.LOG

2018-05-15T14:12:37Z

Xx516:

File:Xx al2cl4br2 1 freqtable.jpg

2018-05-15T14:11:46Z

Xx516:

File:Xx al2cl4br2 1 opt item.PNG

2018-05-15T14:03:50Z

Xx516:

File:Xx al2cl4br2 1 sum.jpg

2018-05-15T14:03:25Z

Xx516:

CCL:lydia

2018-05-15T13:35:13Z

Xx516:

== BH3 Molecule ==

=== Basis set 3-21G and Calculation method RB3LYP ===

==== Summary table ====
[[File:BH3 opt sumXXN.jpg]]

==== Item table ====
[[File:Xx bh3 opt item.jpg]]

=== Basis set 6-31G and Calculation method RB3LYP ===

==== Summary Table ====
[[File:Xx bh3 opt631g sum.jpg]]

==== Item Table ====
[[File:Xx bh3 opt631g item.jpg]]

==== BH3 frequency ====
Frequency File:

[[File:Xx bh3 freq table.jpg]]

The convergence of low frequency values are within the +/-15 region, thus the frequency analysis is complete.

<jmol><jmolApplet>
<title>BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Vibrational spectrum of BH3 molecule ====

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1162.97 || 92.5682 || A2 || Yes || out-of-plane bend
|-
| 1213.14 || 14.0550 || E || Slightly || bend
|-
| 1213.14 || 14.0544 || E || Slightly || bend
|-
| 2582.58 || 0.0000 || A1 || No || Symmetric stretch
|-
| 2715.72 || 126.3320 || E || Yes || Asymmetric stretch
|-
| 2715.72 || 126.3260 || E || Yes || Asymmetric stretch
|}

The vibrational spectrum of BH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, only three peaks can be seen on the spectrum.
The two bend peaks have the same fequency, which lead to the two peaks are present as a whole, same for the two peak correspond to asymmetric streches (same frequency). The symmetric stretch is not IR active since there is no dipole change upon vibration, thus there is no peak on IR spectrum.

[[File:Xx bh3 freq IR.jpg|800px]]

==== BH3 MO diagram ====
[[File:Bh3 full MOs.jpg]]

The above figure shows a BH3 MO diagram with real MO orbitals (the occupied MOs and the LUMO). As shown in the figure, the real MOs look really similar to the LCAO MOs, they have similar in-phase region and out-of-phase region. This proves that the qualitative MO theory is quite accurate and useful in predicting the shape of the MOs.

== NH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3 opt item.PNG]]

=== Frequency optimisation of NH3 molecule ===
Frequency File:

[[File:Xx nh3 freq table.jpg]]
The low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>NH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of NH3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 1088.76 || 145.4214 || A1 || Yes || out-of-plane bend
|-
| 1694.19 || 13.5548 || E || Slightly || bend
|-
| 1694.19 || 13.5549 || E || Slightly || bend
|-
| 3461.00 || 1.0598 || A1 || No || Symmetric stretch
|-
| 3589.74 || 0.2708 || E || No || Asymmetric stretch
|-
| 3589.47 || 0.2709 || E || No || Asymmetric stretch
|}

The vibrational spectrum of NH3 molecule is shown below. Six peaks are expected to see with each corresponding to one vibrational mode. However, there are only two [eaks shown on the spectrum.
Molecular vibrations of symmetric stretch and asymmetric stretch only create a small dipole change, thus, the IR intensity is negligible and the peaks not shown in the IR spectrum.
The two bent vibrations give the same IR frequency, therefore, shown as a single pak on the IR spectrum.
[[File: Xx nh3 freq IR.jpg]]

== NH3BH3 molecule ==

=== Basis set and calculation method ===
Optimisation of the NH3BH3molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

=== Summary table ===
[[File:Xx nh3bh3 opt sum.jpg]]

=== Item table ===
[[File:Xx nh3bh3 opt item.jpg]]

=== Frequency optimisation of NH3BH3 molecule ===

[[File:Xx nh3bh3 freq table.jpg]]

The low frequency values are within the +/-50 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>NH3BH3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Association Energy ===

{| class="wikitable" border="1"
|+ caption
! Molecule !! Energy in au !! Energy in kJmol-1
|-
| NH3 || -56.558au || -35.49*103kJmol-1
|-
| BH3 || -26.462au || -16.60*103kJmol-1
|-
| NH3BH3 || -83.225au || -52.22*103kJmol-1
|}

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]= -130kJmol-1

Therefore, the bond energy of the N-B bond is 130kJmol-1, which indicate the bond being a fairly weak bond compare to the bond energy of the C-C single bond with medium bond energy (348kJmol-1).

== BBr3 molecule ==

=== Basis set and calculation method ===
The optimisation of BBr3 molecule uses calculation method of B3LYP and basis set of GEM.
The frequency optimisation of BBr3 molecule uses calculation method of B3LYP and basis set pf 6-31G(d,p).

=== Summary table ===
[[File:Xx bbr3 sum.jpg]]

=== Item table ===
[[File:Xx bbr3 item.jpg]]

=== Frequency optimisation of BBr3 molecule ===
Frequency File:

[[File:Xx bbr3 freq table.PNG]]
The low frequency values are within the +/-15 region. Thus, the optimisation is complete.

<jmol><jmolApplet>
<title>BBr3 molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX BBR3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Vibrational spectrum of BBr3 molecule ===

{| class="wikitable" border="1"
|+ caption
! Frequency !! IR intensity !! Symmetry !! IR Active !! type
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 150.82 || 0.1354 || E || No || bend
|-
| 279.84 || 0.0000 || A1 || No || Symmetric stretch
|-
| 385.14 || 1.4146 || A2 || No || out-of-plane bend
|-
| 804.59 || 288.4456 || E || Yes || Asymmetric stretch
|-
| 804.63 || 288.4458 || E || Yes || Asymmetric stretch
|}

The below figure is an image of the spectrum of the BBr3. Six peaks are expected to see since there are six vibrational modes. However, there is only one peak on the spectrum. This is due to that there is no dipole change on the molecule upon bend, symmetric stretch and out-of-plane bend, thus the vibrations are IR inactive.

[[File:Xx nh3bh3 freq ir.jpg]]

== Al2Cl4Br2 molecule ==

=== Isomers and point group ===

=== Isomer 1 with Br as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx nh3 freq table.jpg]]
The convergence of the low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>bezene molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Isomer 2 with Cl as bridging molecules ===

==== Basis set and calculation method ====
Optimisation of the Al2Cl4Br2 molecule uses basis set of 6-31G (d,p) and calculation method of RB3LYP.

==== Summary table ====
[[File:Xx al2cl4br2 opt sum.jpg]]

==== Item table ====
[[File:Xx al2cl4br2 opt item.jpg]]

==== Frequency optimisation of Al2Cl4Br2 molecule ====

[File:Xx nh3 freq table.jpg]]
The convergence of the low frequency values are outside the +/-15 region. However, for NH3, the formally zero frequencies are well separated from the lowest energy positive frequency at 1088cm-1 and the large formally zero frequencies are due to the low level of the basis set and relatively relaxed convergence and integration criteria.

<jmol><jmolApplet>
<title>bezene molecule</title>
<color>black</color>
<size>400</size>
<uploadedFileContents>XX NH3BH3 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy comparision of the two isomers ===

=== MOs of the lowest energy conformer ===