ChemWiki - User contributions [en]

Inorgjwy17

2019-05-24T16:48:58Z

Jwy17: /* NH3 BH3 Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>300</size>
<script> frame 1.2 </script>
<uploadedFileContents>JWY17OPTIMISEDBH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/6-31G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1162 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 3|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 4|| 2582 || 0 || No || Symmetric Stretch
|-
| 5 || 2715 || 126 || Yes || Asymmetric Stretch
|-
| 6|| 2715 || 126 || Yes || Asymmetric Stretch
|}
As shown, using different basis sets the vibrational frequency, intensity are slightly different. However, the type of vibration and IR activity of the vibrations remain the same. The IR spectrum therefore, will have peak at slightly different frequencies compared to the 3-21G method, possessing the same relative positions.

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
[[File:Ammonia jwy17.PNG]]

E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>NI3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

File:Ammonia jwy17.PNG

2019-05-24T16:48:40Z

Jwy17:

Inorgjwy17

2019-05-24T16:45:49Z

Jwy17: /* Frequency Analysis (B3LYP/6-31G) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>300</size>
<script> frame 1.2 </script>
<uploadedFileContents>JWY17OPTIMISEDBH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/6-31G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1162 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 3|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 4|| 2582 || 0 || No || Symmetric Stretch
|-
| 5 || 2715 || 126 || Yes || Asymmetric Stretch
|-
| 6|| 2715 || 126 || Yes || Asymmetric Stretch
|}
As shown, using different basis sets the vibrational frequency, intensity are slightly different. However, the type of vibration and IR activity of the vibrations remain the same. The IR spectrum therefore, will have peak at slightly different frequencies compared to the 3-21G method, possessing the same relative positions.

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>NI3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:44:56Z

Jwy17: /* Frequency Analysis (B3LYP/6-31G) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>300</size>
<script> frame 1.2 </script>
<uploadedFileContents>JWY17OPTIMISEDBH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/6-31G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1162 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 3|| 1213 || 14 || Slightly || Scissor (bend)
|-
| 4|| 2582 || 0 || No || Symmetric Stretch
|-
| 5 || 2715 || 126 || Yes || Asymmetric Stretch
|-
| 6|| 2715 || 126 || Yes || Asymmetric Stretch
|}
As shown, using different basis sets the vibrational frequency, intensity are slightly different. However, the type of vibration and IR activity of the vibrations remain the same. The IR spectrum therefore, will have peak at slightly different frequencies, with the same relative positions.

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>NI3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:38:06Z

Jwy17: /* Frequency (B3LYP/3-21G) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>300</size>
<script> frame 1.2 </script>
<uploadedFileContents>JWY17OPTIMISEDBH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>NI3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:37:29Z

Jwy17: /* Frequency (B3LYP/6-31G(d,p)LANL2DZ) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>NI3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:37:17Z

Jwy17: /* Frequency (B3LYP/6-31G(d,p)LANL2DZ) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>300</size>
<uploadedFileContents>NI3 JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:37:00Z

Jwy17: /* Cis - Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>

<jmol><jmolApplet>
<title>Cis - Al2C4Br2 (Red = BR)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRCIS JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:36:43Z

Jwy17: /* Trans - Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>

<jmol><jmolApplet>
<title> Trans-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:36:31Z

Jwy17: /* 2Br Bridge-Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>

<jmol><jmolApplet>
<title> 2Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRBRIDGE JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:36:20Z

Jwy17: /* Al2C4Br2 with terminal and bridging Br */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRMIX JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:36:06Z

Jwy17: /* Al2C4Br2 with 2 Terminal Br */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>

<jmol><jmolApplet>
<title> 2-Br Bridge-Al2C4Br2 </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>AL2CL4BR2 OPT BRTERM JWY17.LOG</uploadedFileContents>
</jmolApplet></jmol>

=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

Inorgjwy17

2019-05-24T16:35:36Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.jpg]]

File:Mini project mo.jpg

2019-05-24T16:35:06Z

Jwy17:

Inorgjwy17

2019-05-24T16:32:46Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:MiniprojectMO.PNG]]

File:MiniprojectMO.PNG

2019-05-24T16:32:34Z

Jwy17: Jwy17 uploaded a new version of File:MiniprojectMO.PNG

Inorgjwy17

2019-05-24T16:29:07Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:File:MiniprojectMO.PNG|centre|thumb|824x824px]]

File:MiniprojectMO.PNG

2019-05-24T16:28:55Z

Jwy17:

Inorgjwy17

2019-05-24T16:25:57Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini_project_mo.png|centre|thumb|824x824px]]

Inorgjwy17

2019-05-24T16:24:57Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===
[[File:Mini project mo.png]]

File:Mini project mo.png

2019-05-24T16:23:55Z

Jwy17:

Inorgjwy17

2019-05-24T16:23:32Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===

Inorgjwy17

2019-05-24T15:09:02Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===

40, 49, 53

Inorgjwy17

2019-05-24T14:38:07Z

Jwy17: /* MO of trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to dimerise and form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===

40,

Inorgjwy17

2019-05-24T14:29:51Z

Jwy17: /* Trans - Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy1763.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to combine to form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===

File:Brtrans jwy1763.PNG

2019-05-24T14:29:29Z

Jwy17:

Inorgjwy17

2019-05-24T14:27:51Z

Jwy17: /* Al2C4Br2 with 2 Terminal Br */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to combine to form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

=== MO of trans-Al2Cl4Br2 ===

File:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG

2019-05-24T14:22:58Z

Jwy17: Jwy17 uploaded a new version of File:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG

Inorgjwy17

2019-05-24T14:19:53Z

Jwy17: /* Trans - Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000055 0.000450 YES
RMS Force 0.000020 0.000300 YES
Maximum Displacement 0.000295 0.001800 YES
RMS Displacement 0.000141 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -1.4581 -0.0018 0.0024 0.0026 0.8584 1.5599
Low frequencies --- 18.1956 49.1682 72.8886
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to combine to form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:Brtrans jwy17.PNG

2019-05-24T14:18:07Z

Jwy17: Jwy17 uploaded a new version of File:Brtrans jwy17.PNG

File:Brtrans summary jwy17.PNG

2019-05-24T14:17:20Z

Jwy17: Jwy17 uploaded a new version of File:Brtrans summary jwy17.PNG

Inorgjwy17

2019-05-24T14:09:00Z

Jwy17: /* Trans-Al2Cl4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

The product is more stable than the isolated monomers, meaning the monomer is more likely to combine to form the product despite the drop in entropy. In the product, both Al-Cl terminal and Al-Cl bridge bond are longer than the Al-Cl bond in the monomer (2.094 Angstrom, 2.299 Angstrom, 2.089 Angstrom respectively). However, the 2 extra Al-Cl bonding in the product more than compensated for the increase in energy from the extended bond length.

==== Al2C4Br2 with 2 Terminal Br ====
[[File:Alclbr2 summary jwy17.PNG|centre|thumb]]
[[File:Alcl3 summary jwy17.PNG|centre|thumb]]
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:Alcl3 summary jwy17.PNG

2019-05-24T14:08:15Z

Jwy17:

File:Alclbr2 summary jwy17.PNG

2019-05-24T14:04:46Z

Jwy17:

Inorgjwy17

2019-05-24T13:52:18Z

Jwy17: /* Trans-Al2Cl4Br2) */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

==== Al2C4Br2 with 2 Terminal Br ====
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

Inorgjwy17

2019-05-24T13:51:55Z

Jwy17: /* Dissociation/Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

==== Trans-Al2Cl4Br2)====
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

==== Al2C4Br2 with 2 Terminal Br ====
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

Inorgjwy17

2019-05-24T13:51:04Z

Jwy17: /* Dissociation/Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===
[[File:Alcl2br jwy17.PNG|frameless]]

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

==== Al2C4Br2 with 2 Terminal Br ====
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:Alcl2br jwy17.PNG

2019-05-24T13:50:22Z

Jwy17:

Inorgjwy17

2019-05-24T13:49:30Z

Jwy17: /* Dissociation/Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

E(AlCl2Br) = -1176.1901 a.u.

E(trans-Al2Cl4Br2) = -2352.4163 a.u.

ΔE = -2352.4163 -(-2 x 1176.1901)

= -0.0361 a.u.

= -95kJ/mol

==== Al2C4Br2 with 2 Terminal Br ====
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

Inorgjwy17

2019-05-24T13:46:20Z

Jwy17: /* Dissociation/Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===

E(AlCl2Br) = -1176.1901

E(

==== Al2C4Br2 with 2 Terminal Br ====
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:Brcis summary jwy17.PNG

2019-05-24T13:33:51Z

Jwy17: Jwy17 uploaded a new version of File:Brcis summary jwy17.PNG

Inorgjwy17

2019-05-24T13:20:47Z

Jwy17: /* 2Br Bridge-Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000119 0.000450 YES
RMS Force 0.000044 0.000300 YES
Maximum Displacement 0.001376 0.001800 YES
RMS Displacement 0.000539 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4581 -5.2150 -2.6435 0.0050 0.0050 0.0051
Low frequencies --- 14.7818 63.1287 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG

2019-05-24T13:20:41Z

Jwy17: Jwy17 uploaded a new version of File:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG

File:Brbridge summary jwy17.PNG

2019-05-24T13:20:22Z

Jwy17: Jwy17 uploaded a new version of File:Brbridge summary jwy17.PNG

Inorgjwy17

2019-05-24T13:15:12Z

Jwy17: /* 2Br Bridge-Al2C4Br2 */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000030 0.000300 YES
Maximum Displacement 0.003840 0.001800 NO
RMS Displacement 0.001767 0.001200 NO

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -5.4574 -5.2144 -2.6432 0.0006 0.0036 0.0037
Low frequencies --- 14.7821 63.1288 85.9458
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

File:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG

2019-05-24T13:14:58Z

Jwy17: Jwy17 uploaded a new version of File:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG

File:Brbridge summary jwy17.PNG

2019-05-24T13:12:29Z

Jwy17: Jwy17 uploaded a new version of File:Brbridge summary jwy17.PNG

File:Brterm sumary jwy17.PNG

2019-05-24T13:04:21Z

Jwy17: Jwy17 uploaded a new version of File:Brterm sumary jwy17.PNG

Inorgjwy17

2019-05-24T11:49:47Z

Jwy17: /* Dissociation/Association Energy */

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.036754 0.000450 NO
RMS Force 0.016461 0.000300 NO
Maximum Displacement 0.124812 0.001800 NO
RMS Displacement 0.044741 0.001200 NO

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -0.8362 -0.0040 -0.0039 -0.0022 0.4660 1.5093
Low frequencies --- 16.0873 63.5920 86.0704
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) = - 2352.4163 a.u.

ΔE = - 2352.4163 - (-5846.2639 -1623.2333)

= 5117.0809 a.u.

= 1.35 x 10^4 kJ/mol

The isolated monomers are overwhelmingly more stable than the product. Based on the bond length changes, the Al-Br bond in the product is weaker than the monomer (Product: 2.277 Angstrom, AlClBr2 Monomer = 2.238 Angstrom). The Al-Cl bridge bond strength in the product is also significantly larger than the monomers (Al-Cl bridge: 2.301, AlClBr2: Al-Cl = 2.095 Angstrom, AlCl3: Al-Cl = 2.087 Angstrom). The longer bonds in the product molecule despite the 2 extra Al-Cl bridge bond seemed to increase the overall energy of the product.

Inorgjwy17

2019-05-24T11:25:13Z

Jwy17:

== Molecule Computational Analysis ==

=== BH3 ===

==== B3LYP/3-21G Method ====
[[File:321 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000206 0.000450 YES
RMS Force 0.000107 0.000300 YES
Maximum Displacement 0.001134 0.001800 YES
RMS Displacement 0.000605 0.001200 YES
</pre>

==== Frequency (B3LYP/3-21G) ====
Link to Frequency Analysis .log file [[Media:JWY17OPTIMISEDBH3_FREQ.LOG|B3LYP/3-21G BH3 Frequency]]

<pre>
Low frequencies --- 0.0004 0.0005 0.0006 40.7057 42.0009 47.9484
Low frequencies --- 1146.2825 1204.7702 1204.93534.9353</pre>



{| class="wikitable" border="1"
|+ Frequency Analysis of BH3 B3LYP/3-21G
! Mode !! Frequency !! Intensity (arbitrary unit) !! IR active? !! Type
|-
| 1 || 1146 || 92 || Yes || Out-of-plane Bend
|-
| 2|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 3|| 1205 || 12 || Slightly || Scissor (bend)
|-
| 4|| 2591 || 0 || No || Symmetric Stretch
|-
| 5 || 2729 || 104 || Yes || Asymmetric Stretch
|-
| 6|| 2729 || 104 || Yes || Asymmetric Stretch
|}

[[File:Jwy17 IR BH3 321.png| 500px]]

The reasons for 3 peaks in the IR spectrum despite having 6 vibrational modes are:

1. The lack of dipole moment change in vibrational mode 4. This means it is not IR active and no peak for this particular vibration.

2. The degeneracy of mode 2,3 and 5,6. Their peaks would overlap and form a single peak. This explains, as well, why the peak at 2729cm-1 is almost double the height of the peak at 1146cm-1.

==== B3LYP/6-31G Method ====
[[File:631 BH3 summary jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000014 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000055 0.001800 YES
RMS Displacement 0.000027 0.001200 YES
</pre>

==== Frequency Analysis (B3LYP/6-31G) ====
Link to Frequency Analysis .log file [[Media:JWY17_BH3_6-31G_FREQ.LOG|B3LYP/6-31G BH3 Frequency]]

The vibrational modes, frequencies and IR Spectrum are identical to the ones using the B3LYP/3-21G method,

==== MO diagram and Orbitals ====
[[File:MO BH3 jwy17.jpg|centre|thumb|The generated orbitals are not too different from the orbitals formed through LCAO methods. For simple molecules, the LCAO method is a quick to way to predict the molecular orbitals the molecule has.]]

=== NH3 BH3 Association Energy ===
E(NH3)= -56.5566 a.u.

E(BH3)= -26.6153 a.u.

E(NH3BH3)= -83.2247 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.0528 a.u

= -138.95 kJ/Mol

Compared to ethane C-C bond (376.56kJ/Mol), the B-N bond is only about a third as strong, therefore the B-N bond is considered medium strong relative to the ethane C-C bond.

=== NI3 ===

==== B3LYP/6-31G(d,p)LANL2DZ Method ====
[[File:NI3 jwy17.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000028 0.000450 YES
RMS Force 0.000014 0.000300 YES
Maximum Displacement 0.000242 0.001800 YES
RMS Displacement 0.000122 0.001200 YES
</pre>

==== Frequency (B3LYP/6-31G(d,p)LANL2DZ) ====
Link to Frequency Analysis .log file [[Media:NI3 JWY17 FREQ.LOG|NI3 Frequency]]

<pre>
Low frequencies --- -0.0576 -0.0292 -0.0031 1.9682 2.0035 2.2189
Low frequencies --- 101.3080 101.3087 148.3159
</pre>



==== N-I distance ====
The optimised molecule gave a N-I bond distance of 2.184 Angstrom.

== Mini-Project: Al2Cl4Br2 ==

=== Isomers ===
==== Cis - Al2C4Br2 ====
[[File:Brcis summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000030 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000393 0.001800 YES
RMS Displacement 0.000164 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRCIS JWY17.LOG|Cis-Al2C4Br2]]

<pre>
Low frequencies --- -1.4145 -0.5292 -0.0017 -0.0003 0.0002 2.3603
Low frequencies --- 17.4891 51.1468 78.5185
</pre>



==== Trans - Al2C4Br2 ====
[[File:Brtrans summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000084 0.000450 YES
RMS Force 0.000026 0.000300 YES
Maximum Displacement 0.000959 0.001800 YES
RMS Displacement 0.000438 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT TRANS JWY17 FREQ.LOG|Trans-Al2C4Br2]]

<pre>
Low frequencies --- -2.5199 -1.5214 -0.6913 0.0013 0.0021 0.0023
Low frequencies --- 18.1634 49.1614 72.8885
</pre>



====2Br Bridge-Al2C4Br2 ====
[[File:Brbridge summary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.036754 0.000450 NO
RMS Force 0.016461 0.000300 NO
Maximum Displacement 0.124812 0.001800 NO
RMS Displacement 0.044741 0.001200 NO

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRBRIDGE JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -0.8362 -0.0040 -0.0039 -0.0022 0.4660 1.5093
Low frequencies --- 16.0873 63.5920 86.0704
</pre>



==== Al2C4Br2 with terminal and bridging Br ====
[[File:Brmis summary jwy17.PNG|frameless]]

The molecule is an enantiomer, which the other is the mirror image of the one shown. In a non chiral environment, they both posses the same vibrational modes and energy.

<pre>
Item Value Threshold Converged?
Maximum Force 0.000049 0.000450 YES
RMS Force 0.000019 0.000300 YES
Maximum Displacement 0.001173 0.001800 YES
RMS Displacement 0.000344 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRMIX JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- -1.2949 -0.0032 -0.0029 -0.0018 1.2691 1.6593
Low frequencies --- 16.9144 55.8709 80.0771
</pre>



==== Al2C4Br2 with 2 Terminal Br ====
[[File:Brterm sumary jwy17.PNG|frameless]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000050 0.000450 YES
RMS Force 0.000017 0.000300 YES
Maximum Displacement 0.001034 0.001800 YES
RMS Displacement 0.000357 0.001200 YES

</pre>
Link to Frequency Analysis .log file [[Media:AL2CL4BR2 OPT BRTERM JWY17.LOG|2-Br Bridge-Al2C4Br2]]

<pre>
Low frequencies --- 0.0030 0.0035 0.0036 0.5786 0.9759 2.2139
Low frequencies --- 18.7071 51.2220 72.1983
</pre>



=== Energy ===
E(trans-Al2Cl4Br2) = -2352.4163 a.u.

E(2-Br Bridge-Al2Cl4Br2) = -2352.4063 a.u.

ΔE = 0.0100 a.u.

= 26kJ/mol

Therefore, the trans-Al2Cl4Br2 is the more stable isomer of the 2. However, among all the isomers of the molecule, Al2Cl4Br2 with 2 terminal Br is the lowest in energy.

=== Dissociation/Association Energy ===
E(AlCl3) = -1623.2333 a.u.

E(AlClBr2) = -5846.2639 a.u.

E(Al2Cl4Br2 with 2 terminal Br) =