==EX3==
===BH3===

[[File:Dv1.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000009 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000034 0.001800 YES
RMS Displacement 0.000017 0.001200 YES</pre>

<pre>Low frequencies --- -2.2126 -1.0751 -0.0054 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784</pre>

Link to log file [[File:DV_BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ Infrared Modes of BH3
! Mode !! Wavenumber /cm-1 !! Intesity/Arbitrary Units!! IR active !! Symmetry !! Vibration Type
|-
| 1 || 1163 || 92 || yes|| A2'''' || out of plane bending
|-
| 2 || 1213 || 14 || yes|| E' || rock bend
|-
| 3 || 1213 || 14|| yes|| E' || rock bend
|-
| 4 || 2582 || 0 || no|| A1' || symmetric stretch(no change in dipole moment)
|-
| 5 || 2715 || 126|| yes|| E' || Asymetric stretch
|-
| 6 || 2715 || 126 || yes|| E' || Asymmetric stretch
|}

[[File:Figure3dv.PNG]]

The obtained computational results shows there are 6 vibrational modes, it is expected 3 modes following the 3N-6 rule. The spectrum above only shows 3 peaks, modes 2&3 and modes 5&6 have degenerate energy relative to one another, so only appear as one peak in the spectrum. On the other hand, mode 4 corresponds to a symmetric stretch which does not appear in the spectrum because there's no change in dipole moment involved. That gives two peaks so far, such that the remaining peak is due to non-degenerate out of plane bending.

'''MO Analysis'''

[[File:Figure4dv.PNG]]

By comparing the quantified MOs obtained in Gaussian to those expected by applying LCAO, it is seen that the MOs come out as expected in terms of relative shape and phases. This is a simple MO diagram because there are only 4 atoms involved in a symmetric arrangement in an 8 electron system. It is seen that for the unfilled higher energy MOs the electron density is more diffuse and the shape of the MOs becomes harder to interpret relative to the MOs expected from LCAO theory.

===NH3===

[[File:Figure5dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000092 0.000450 YES
RMS Force 0.000039 0.000300 YES
Maximum Displacement 0.000304 0.001800 YES
RMS Displacement 0.000101 0.001200 YES </pre>

<pre> Low frequencies --- -32.4128 -32.3999 -11.4544 -0.0040 0.0076 0.0521
Low frequencies --- 1088.7642 1694.0248 1694.0252 </pre>

Link to log file [[File:DV_NH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

===NH3BH3===

[[File:Figure7dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000114 0.000450 YES
RMS Force 0.000063 0.000300 YES
Maximum Displacement 0.000621 0.001800 YES
RMS Displacement 0.000355 0.001200 YES</pre>

<pre>Low frequencies --- -0.0617 -0.0457 -0.0067 21.6783 21.6842 40.5400
Low frequencies --- 266.0169 632.3610 640.1360 </pre>

Link to log file [[File:DV_NH3BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

•E(NH3)= -56.55777 a.u.

•E(BH3)= -26.61532 a.u.

•E(NH3BH3)= -83.22469 a.u.

•ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22469 - (-26.61532-56.55777)

•ΔE = -0.05160 a.u. = -135 kJmol-1

The B-N bond is of dative covalent nature, though there's a strong dipole moment across the bond due to the difference in electronegativity between boron and nitrogen, by comparing to the strength of C-C bond -348 kJmol -1, C-C is around 2.5 times stronger than the dative covalent B-N bond.

===BBr3===

[[File:Figure8dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000018 0.001200 YES </pre>

<pre>Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421
Low frequencies --- 155.9631 155.9651 267.7052 </pre>

Link to log file [[File:DV_BBr3_pseudo_freq_run1.log]]

<jmol><jmolApplet>
<title>BBr3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BBr3_pseudo_freq_run1.log</uploadedFileContents>
</jmolApplet></jmol>

{{DOI|10042/202400}}

==Mini Project==

Isomers of Al2Br2Cl4 were investigated in this section

[[File:Figure9dv.PNG]]

Aluminium and Chlorine atoms optimised with B3LYP/6-31G(d,p) and Br atoms optimised with LanL2DZ pseudopotentials.

===Isomer i (Bridging Br)===

[[File:Figure10dv.PNG]]

Isomer i) energy = -2352.40631 a.u. = -6175067 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000002 0.000300 YES
Maximum Displacement 0.000604 0.001800 YES
RMS Displacement 0.000310 0.001200 YES</pre>

<pre>Low frequencies --- -5.1748 -5.0356 -3.1468 -0.0023 -0.0011 0.0005
Low frequencies --- 14.8260 63.2702 86.0770</pre>

Link to log file [[File:ISO1_AL2BR2CL4_FREQ11.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO1_AL2BR2CL4_FREQ11.LOG</uploadedFileContents>
</jmolApplet></jmol>

===Isomer ii (Bridging Cl with trans terminal Br)===

[[File:Figure11dv.PNG]]

Isomer ii energy = -2352.41630 a.u. = -6175093 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000023 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000863 0.001800 YES
RMS Displacement 0.000319 0.001200 YES</pre>

<pre>Low frequencies --- -4.9721 0.0023 0.0023 0.0027 1.6380 2.3324
Low frequencies --- 18.1768 49.0937 73.0114</pre>

Link to log file [[File:ISO2_AL2BR2CL4_FREQ1.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO2_AL2BR2CL4_FREQ1.LOG</uploadedFileContents>
</jmolApplet></jmol>

•Isomer i energy = -6175067 kJmol-1

•Isomer ii energy = -6175093 kJmol-1

•Energy difference = -6175093 kJmol-1 + 6175067 kJmol-1 = -26 kJmol-1

The second isomer in which there are bridging chlorines instead of bromines is more stable by about -26 kJmol-1. By considering the orbital overlap and match in energy it is seen that there should be better orbital overlap and match in energy between Al and Cl than between Al and Br because the first two are in the same row in the periodic table, whereas the latter two would lead to more diffuse orbital overlap and higher energy mismatch as Br is in row 4 of the periodic table.

===AlCl2Br===

[[File:Figure17dv.PNG]]

AlCl2Br energy = -1176.19014 a.u. = -3087499 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000136 0.000450 YES
RMS Force 0.000073 0.000300 YES
Maximum Displacement 0.000760 0.001800 YES
RMS Displacement 0.000497 0.001200 YES
</pre>

<pre> Low frequencies --- 0.0042 0.0049 0.0050 1.3569 3.6367 4.2604
Low frequencies --- 120.5042 133.9178 185.8950 </pre>

Energy of dimer = -6175093 kJmol-1

Energy of AlCl2Br = -3087499 kJmol-1

Dissociation Energy = 2E(monomer) -E(Isomer) = 95 kJmol-1

The calculation shows that formation of the dimer is favourable by 95 kJmol-1. This is because as a monomer the sp2 Aluminium centre has a 6 valence electron shell, but by dimerising there's donation of electron density from the bridging chlorine atoms to relieve the electron defficiency on the Aluminium atom.

Link to log file [[File:ALCL2BR_FREQ_RUN3.log]]

<jmol><jmolApplet>
<title>ALCL2BR monomer </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ALCL2BR_FREQ_RUN3.log</uploadedFileContents>
</jmolApplet></jmol>

===MO analysis===

'''MO 40'''

[[File:Figure13dv.PNG]]

Fragment Orbitals

[[File:Figure24dv.PNG]]

[[File:Figure23dv.PNG]]

Interactions

1) medium distance, but s-s orbitals through space antibonding interaction so overall medium antibonding

2) bonding interaction, small distance but p orbitals, so overall strong bonding interaction

3) s-p interaction, short distance, but overlaps out of phase . The terminal orbitals look more like polarised s orbitals than p orbitals. The bonding interactions are outweighed by the antibonding interactions so overall antibonding .

The delocalised pi system prevails in the MO but the other picture on the right shows the nodes on the dimer which also show the MO is overall weakly antibonding̟.

'''MO 48'''

[[File:Figure16dv.PNG]]

Fragment Orbitals

[[File:Figure32dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2)Medium range, through space orbital interaction therefore medium bonding

3) Small distance,spatial overlap but orbitals have lower contribution to the MO and are slightly polarised, sigma type so medium bonding

4) Medium range, through space orbital overlap, in phase bonding

The contributions from the terminal Chlorine p orbitals is greater than that of the terminal bromine p orbitals. The MO is overall weakly bonding.

''' MO 54'''

[[File:Figure18dv.PNG]]

Fragment Orbitals

[[File:Figure31dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2) Medium range, through space orbital interaction, out of phase so weakly antibonding

3) medium range, through space orbital interaction, out of phase so is weakly antibonding

4)small distance, through space orbital interaction, sideways interaction so weakly bonding

The MO is assigned as antibonding, the antibonding interactions outweigh the bonding interactions.The contribution from the bromine atoms is greater than that of the chlorine atoms also suggests that this is an antibonding MO.

2018-05-24T15:48:38Z

Dav16: /* AlCl2Br */

==EX3==
===BH3===

[[File:Dv1.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000009 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000034 0.001800 YES
RMS Displacement 0.000017 0.001200 YES</pre>

<pre>Low frequencies --- -2.2126 -1.0751 -0.0054 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784</pre>

Link to log file [[File:DV_BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ CAPTION
! Mode !! Wavenumber /cm-1 !! Intesity/Arbitrary Units!! IR active !! Symmetry !! Vibration Type
|-
| 1 || 1163 || 92 || yes|| A2'''' || out of plane bending
|-
| 2 || 1213 || 14 || yes|| E' || rock bend
|-
| 3 || 1213 || 14|| yes|| E' || rock bend
|-
| 4 || 2582 || 0 || no|| A1' || symmetric stretch(no change in dipole moment)
|-
| 5 || 2715 || 126|| yes|| E' || Asymetric stretch
|-
| 6 || 2715 || 126 || yes|| E' || Asymmetric stretch
|}

[[File:Figure3dv.PNG]]

The obtained computational results there are 6 vibrational modes, it is expected 3 modes following the 3N-6 rule. The spectrum above only shows 3 peaks, modes 2&3 and modes 5&6 have degenerate energy relative to one another, so only appear as one peak in the spectrum. On the other hand, mode 4 corresponds to a symmetric stretch which does not appear in the spectrum because there's no change in dipole moment involved. That gives two peaks so far, such that the remaining peak is due to non-degenerate out of plane bending.

'''MO Analysis'''

[[File:Figure4dv.PNG]]

By comparing the quantified MOs obtained in Gaussian to those expected by applying LCAO, it is seen that the MOs come out as expected in terms of shape and phases. This is a simple MO diagram because there are only 4 atoms involved in a symmetric arrangement in an 8 electron system. It is seen that for the higher energy MOs the electron density is more diffuse and the shape of the MOs becomes harder to interpret relative to the MOs expected from theory.

===NH3===

[[File:Figure5dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000092 0.000450 YES
RMS Force 0.000039 0.000300 YES
Maximum Displacement 0.000304 0.001800 YES
RMS Displacement 0.000101 0.001200 YES </pre>

<pre> Low frequencies --- -32.4128 -32.3999 -11.4544 -0.0040 0.0076 0.0521
Low frequencies --- 1088.7642 1694.0248 1694.0252 </pre>

Link to log file [[File:DV_NH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

===NH3BH3===

[[File:Figure7dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000114 0.000450 YES
RMS Force 0.000063 0.000300 YES
Maximum Displacement 0.000621 0.001800 YES
RMS Displacement 0.000355 0.001200 YES</pre>

<pre>Low frequencies --- -0.0617 -0.0457 -0.0067 21.6783 21.6842 40.5400
Low frequencies --- 266.0169 632.3610 640.1360 </pre>

Link to log file [[File:DV_NH3BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

•E(NH3)= -56.55777 a.u.

•E(BH3)= -26.61532 a.u.

•E(NH3BH3)= -83.22469 a.u.

•ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22469 - (-26.61532-56.55777)

•ΔE = -0.05160 a.u. = -135 kJmol-1

The B-N bond is of dative covalent nature, though there's a strong dipole moment across the bond due to the difference in electronegativity between boron and nitrogen, by comparing to the strength of C-C bond -348 kJmol -1, B-N is a much weaker bond.

===BBr3===

[[File:Figure8dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000018 0.001200 YES </pre>

<pre>Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421
Low frequencies --- 155.9631 155.9651 267.7052 </pre>

Link to log file [[File:DV_BBr3_pseudo_freq_run1.log]]

<jmol><jmolApplet>
<title>BBr3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BBr3_pseudo_freq_run1.log</uploadedFileContents>
</jmolApplet></jmol>

{{DOI|10042/202400}}

==Mini Project==

Isomers of Al2Br2Cl4 were investigated in this section

[[File:Figure9dv.PNG]]

Aluminium and Chlorine atoms optimised with B3LYP/6-31G(d,p) and BR atoms optimised with LanL2DZ pseudopotentials.

===Isomer i (Bridging Br)===

[[File:Figure10dv.PNG]]

Isomer i) energy = -2352.40631 a.u. = -6175067 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000002 0.000300 YES
Maximum Displacement 0.000604 0.001800 YES
RMS Displacement 0.000310 0.001200 YES</pre>

<pre>Low frequencies --- -5.1748 -5.0356 -3.1468 -0.0023 -0.0011 0.0005
Low frequencies --- 14.8260 63.2702 86.0770</pre>

Link to log file [[File:ISO1_AL2BR2CL4_FREQ11.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO1_AL2BR2CL4_FREQ11.LOG</uploadedFileContents>
</jmolApplet></jmol>

===Isomer ii (Bridging Cl with trans terminal Br)===

[[File:Figure11dv.PNG]]

Isomer ii energy = -2352.41630 a.u. = -6175093 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000023 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000863 0.001800 YES
RMS Displacement 0.000319 0.001200 YES</pre>

<pre>Low frequencies --- -4.9721 0.0023 0.0023 0.0027 1.6380 2.3324
Low frequencies --- 18.1768 49.0937 73.0114</pre>

Link to log file [[File:ISO2_AL2BR2CL4_FREQ1.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO2_AL2BR2CL4_FREQ1.LOG</uploadedFileContents>
</jmolApplet></jmol>

•isomer i energy = -6175067 kJmol-1

•isomer ii energy = -6175093 kJmol-1

The second isomer in which there are bridging chlorines instead of bromines is more stable. By considering the orbital overlap and match in energy it is seen that there should be better orbital overlap and match in energy between Al and Cl than between Al and Br because the first two are in the same row in the periodic table, whereas the latter two would lead to more diffuse orbital overlap as Br is in row 4 of the periodic table.

===AlCl2Br===

[[File:Figure17dv.PNG]]

AlCl2Br energy = -1176.19014 a.u. = -3087499 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000136 0.000450 YES
RMS Force 0.000073 0.000300 YES
Maximum Displacement 0.000760 0.001800 YES
RMS Displacement 0.000497 0.001200 YES
</pre>

<pre> Low frequencies --- 0.0042 0.0049 0.0050 1.3569 3.6367 4.2604
Low frequencies --- 120.5042 133.9178 185.8950 </pre>

Energy of dimer = -6175093 kJmol-1

Energy of AlCl2Br = -3087499 kJmol-1

Dissociation Energy = 2E(monomer) -E(Isomer) = 95 kJmol-1

Link to log file [[File:ALCL2BR_FREQ_RUN3.log]]

<jmol><jmolApplet>
<title>ALCL2BR monomer </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ALCL2BR_FREQ_RUN3.log</uploadedFileContents>
</jmolApplet></jmol>

===MO analysis===

'''MO 40'''

[[File:Figure13dv.PNG]]

Fragment Orbitals

[[File:Figure24dv.PNG]]

[[File:Figure23dv.PNG]]

Interactions

1) medium distance, but s-s orbitals through space antibonding interaction so overall medium antibonding

2) bonding interaction, small distance but p orbitals, so overall strong bonding interaction

3) s-p interaction, short distance, but overlaps out of phase . The terminal orbitals look more like polarised s orbitals than p orbitals. The bonding interactions are outweighed by the antibonding interactions so overall antibonding .

The delocalised pi system prevails in the MO but the other picture on the right shows the nodes on the dimer which also show the MO is overall weakly antibonding̟.

'''MO 48'''

[[File:Figure16dv.PNG]]

Fragment Orbitals

[[File:Figure30dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2)Medium range, through space orbital interaction therefore weakly bonding

3) Small distance,spatial overlap but orbitals have lower contribution to the MO and are slightly polarised, sigma type so medium bonding

The contributions from the terminal Chlorine p orbitals is greater than that of the terminal bromine p orbitals. The MO is overall weakly bonding.

''' MO 54'''

[[File:Figure18dv.PNG]]

Fragment Orbitals

[[File:Figure31dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2) Medium range, through space orbital interaction, out of phase so weakly antibonding

3) medium range, through space orbital interaction, out of phase so is weakly antibonding

4)small distance, through space orbital interaction, sideways interaction so weakly bonding

The MO is assigned as antibonding, the antibonding interactions outweigh the bonding interactions.

Rep:Mod:dav162

2018-05-23T16:05:21Z

Dav16: /* EX3 */

==EX3==
===BH3===

[[File:Dv1.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000009 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000034 0.001800 YES
RMS Displacement 0.000017 0.001200 YES</pre>

<pre>Low frequencies --- -2.2126 -1.0751 -0.0054 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784</pre>

Link to log file [[File:DV_BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ CAPTION
! Mode !! Wavenumber /cm-1 !! Intesity/Arbitrary Units!! IR active !! Symmetry !! Vibration Type
|-
| 1 || 1163 || 92 || yes|| A2'''' || out of plane bending
|-
| 2 || 1213 || 14 || yes|| E' || rock bend
|-
| 3 || 1213 || 14|| yes|| E' || rock bend
|-
| 4 || 2582 || 0 || no|| A1' || symmetric stretch(no change in dipole moment)
|-
| 5 || 2715 || 126|| yes|| E' || Asymetric stretch
|-
| 6 || 2715 || 126 || yes|| E' || Asymmetric stretch
|}

[[File:Figure3dv.PNG]]

The obtained computational results there are 6 vibrational modes, it is expected 3 modes following the 3N-6 rule. The spectrum above only shows 3 peaks, modes 2&3 and modes 5&6 have degenerate energy relative to one another, so only appear as one peak in the spectrum. On the other hand, mode 4 corresponds to a symmetric stretch which does not appear in the spectrum because there's no change in dipole moment involved. That gives two peaks so far, such that the remaining peak is due to non-degenerate out of plane bending.

'''MO Analysis'''

[[File:Figure4dv.PNG]]

By comparing the quantified MOs obtained in Gaussian to those expected by applying LCAO, it is seen that the MOs come out as expected in terms of shape and phases. This is a simple MO diagram because there are only 4 atoms involved in a symmetric arrangement in an 8 electron system. It is seen that for the higher energy MOs the electron density is more diffuse and the shape of the MOs becomes harder to interpret relative to the MOs expected from theory.

===NH3===

[[File:Figure5dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000092 0.000450 YES
RMS Force 0.000039 0.000300 YES
Maximum Displacement 0.000304 0.001800 YES
RMS Displacement 0.000101 0.001200 YES </pre>

<pre> Low frequencies --- -32.4128 -32.3999 -11.4544 -0.0040 0.0076 0.0521
Low frequencies --- 1088.7642 1694.0248 1694.0252 </pre>

Link to log file [[File:DV_NH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

===NH3BH3===

[[File:Figure7dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000114 0.000450 YES
RMS Force 0.000063 0.000300 YES
Maximum Displacement 0.000621 0.001800 YES
RMS Displacement 0.000355 0.001200 YES</pre>

<pre>Low frequencies --- -0.0617 -0.0457 -0.0067 21.6783 21.6842 40.5400
Low frequencies --- 266.0169 632.3610 640.1360 </pre>

Link to log file [[File:DV_NH3BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

•E(NH3)= -56.55777 a.u.

•E(BH3)= -26.61532 a.u.

•E(NH3BH3)= -83.22469 a.u.

•ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22469 - (-26.61532-56.55777)

•ΔE = -0.05160 a.u. = -135 kJmol-1

The B-N bond is of dative covalent nature, though there's a strong dipole moment across the bond due to the difference in electronegativity between boron and nitrogen, by comparing to the strength of C-C bond -348 kJmol -1, B-N is a much weaker bond.

===BBr3===

[[File:Figure8dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000018 0.001200 YES </pre>

<pre>Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421
Low frequencies --- 155.9631 155.9651 267.7052 </pre>

Link to log file [[File:DV_BBr3_pseudo_freq_run1.log]]

<jmol><jmolApplet>
<title>BBr3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BBr3_pseudo_freq_run1.log</uploadedFileContents>
</jmolApplet></jmol>

{{DOI|10042/202400}}

==Mini Project==

Isomers of Al2Br2Cl4 were investigated in this section

[[File:Figure9dv.PNG]]

Aluminium and Chlorine atoms optimised with B3LYP/6-31G(d,p) and BR atoms optimised with LanL2DZ pseudopotentials.

===Isomer i (Bridging Br)===

[[File:Figure10dv.PNG]]

Isomer i) energy = -2352.40631 a.u. = -6175067 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000002 0.000300 YES
Maximum Displacement 0.000604 0.001800 YES
RMS Displacement 0.000310 0.001200 YES</pre>

<pre>Low frequencies --- -5.1748 -5.0356 -3.1468 -0.0023 -0.0011 0.0005
Low frequencies --- 14.8260 63.2702 86.0770</pre>

Link to log file [[File:ISO1_AL2BR2CL4_FREQ11.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO1_AL2BR2CL4_FREQ11.LOG</uploadedFileContents>
</jmolApplet></jmol>

===Isomer ii (Bridging Cl with trans terminal Br)===

[[File:Figure11dv.PNG]]

Isomer ii energy = -2352.41630 a.u. = -6175093 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000023 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000863 0.001800 YES
RMS Displacement 0.000319 0.001200 YES</pre>

<pre>Low frequencies --- -4.9721 0.0023 0.0023 0.0027 1.6380 2.3324
Low frequencies --- 18.1768 49.0937 73.0114</pre>

Link to log file [[File:ISO2_AL2BR2CL4_FREQ1.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO2_AL2BR2CL4_FREQ1.LOG</uploadedFileContents>
</jmolApplet></jmol>

•isomer i energy = -6175067 kJmol-1

•isomer ii energy = -6175093 kJmol-1

The second isomer in which there are bridging chlorines instead of bromines is more stable. By considering the orbital overlap and match in energy it is seen that there should be better orbital overlap and match in energy between Al and Cl than between Al and Br because the first two are in the same row in the periodic table, whereas the latter two would lead to more diffuse orbital overlap as Br is in row 4 of the periodic table.

===AlCl2Br===

[[File:Figure17dv.PNG]]

AlCl2Br energy = -1176.19013679 a.u. = -3087499 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000136 0.000450 YES
RMS Force 0.000073 0.000300 YES
Maximum Displacement 0.000760 0.001800 YES
RMS Displacement 0.000497 0.001200 YES
</pre>

<pre> Low frequencies --- 0.0042 0.0049 0.0050 1.3569 3.6367 4.2604
Low frequencies --- 120.5042 133.9178 185.8950 </pre>

Energy of dimer = -6175093 kJmol-1

Energy of AlCl2Br = -3087499 kJmol-1

Dissociation Energy = 2E(monomer) -E(Isomer) = 95 kJmol-1

Link to log file [[File:ALCL2BR_FREQ_RUN3.log]]

<jmol><jmolApplet>
<title>ALCL2BR monomer </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ALCL2BR_FREQ_RUN3.log</uploadedFileContents>
</jmolApplet></jmol>

===MO analysis===

'''MO 40'''

[[File:Figure13dv.PNG]]

Fragment Orbitals

[[File:Figure24dv.PNG]]

[[File:Figure23dv.PNG]]

Interactions

1) medium distance, but s-s orbitals through space antibonding interaction so overall medium antibonding

2) bonding interaction, small distance but p orbitals, so overall strong bonding interaction

3) s-p interaction, short distance, but overlaps out of phase . The terminal orbitals look more like polarised s orbitals than p orbitals. The bonding interactions are outweighed by the antibonding interactions so overall antibonding .

The delocalised pi system prevails in the MO but the other picture on the right shows the nodes on the dimer which also show the MO is overall weakly antibonding̟.

'''MO 48'''

[[File:Figure16dv.PNG]]

Fragment Orbitals

[[File:Figure30dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2)Medium range, through space orbital interaction therefore weakly bonding

3) Small distance,spatial overlap but orbitals have lower contribution to the MO and are slightly polarised, sigma type so medium bonding

The contributions from the terminal Chlorine p orbitals is greater than that of the terminal bromine p orbitals. The MO is overall weakly bonding.

''' MO 54'''

[[File:Figure18dv.PNG]]

Fragment Orbitals

[[File:Figure31dv.PNG]]

Interactions

1) Long range, through space orbital interaction but far away so very weakly bonding

2) Medium range, through space orbital interaction, out of phase so weakly antibonding

3) medium range, through space orbital interaction, out of phase so is weakly antibonding

4)small distance, through space orbital interaction, sideways interaction so weakly bonding

The MO is assigned as antibonding, the antibonding interactions outweigh the bonding interactions.

2018-05-23T15:02:24Z

Dav16:

Rep:Mod:dav16

2018-05-23T14:50:54Z

Dav16:

Rep:Mod:dav16

2018-05-23T13:53:35Z

Dav16: /* MO analysis */

==EX3==
===BH3===

[[File:Dv1.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000009 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000034 0.001800 YES
RMS Displacement 0.000017 0.001200 YES</pre>

<pre>Low frequencies --- -2.2126 -1.0751 -0.0054 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784</pre>

Link to log file [[File:DV_BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ CAPTION
! Mode !! Wavenumber /cm-1 !! Intesity/Arbitrary Units!! IR active !! Symmetry !! Vibration Type
|-
| 1 || 1163 || 92 || yes|| A2'''' || out of plane bending
|-
| 2 || 1213 || 14 || yes|| E' || rock bend
|-
| 3 || 1213 || 14|| yes|| E' || rock bend
|-
| 4 || 2582 || 0 || no|| A1' || symmetric stretch(no change in dipole moment)
|-
| 5 || 2715 || 126|| yes|| E' || Asymetric stretch
|-
| 6 || 2715 || 126 || yes|| E' || Asymmetric stretch
|}

[[File:Figure3dv.PNG]]

The obtained computational results there are 6 vibrational modes, it is expected 3 modes following the 3N-6 rule. The spectrum above only shows 3 peaks, modes 2&3 and modes 5&6 have degenerate energy relative to one another, so only appear as one peak in the spectrum. On the other hand, mode 4 corresponds to a symmetric stretch which does not appear in the spectrum because there's no change in dipole moment involved. That gives two peaks so far, such that the remaining peak is due to non-degenerate out of plane bending.

'''MO Analysis'''

[[File:Figure4dv.PNG]]

By comparing the quantified MOs obtained in Gaussian to those expected by applying LCAO, it is seen that the MOs come out as expected in terms of shape and phases. This is a simple MO diagram because there are only 4 atoms involved in a symmetric arrangement in an 8 electron system. It is seen that for the higher energy MOs the electron density is more diffuse and the shape of the MOs becomes harder to interpret relative to the MOs expected from theory.

===NH3===

[[File:Figure5dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000092 0.000450 YES
RMS Force 0.000039 0.000300 YES
Maximum Displacement 0.000304 0.001800 YES
RMS Displacement 0.000101 0.001200 YES </pre>

<pre> Low frequencies --- -32.4128 -32.3999 -11.4544 -0.0040 0.0076 0.0521
Low frequencies --- 1088.7642 1694.0248 1694.0252 </pre>

Link to log file [[File:DV_NH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

===NH3BH3===

[[File:Figure7dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000114 0.000450 YES
RMS Force 0.000063 0.000300 YES
Maximum Displacement 0.000621 0.001800 YES
RMS Displacement 0.000355 0.001200 YES</pre>

<pre>Low frequencies --- -0.0617 -0.0457 -0.0067 21.6783 21.6842 40.5400
Low frequencies --- 266.0169 632.3610 640.1360 </pre>

Link to log file [[File:DV_NH3BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

•E(NH3)= -56.55777 a.u.

•E(BH3)= -26.61532 a.u.

•E(NH3BH3)= -83.22469 a.u.

•ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22469 - (-26.61532-56.55777)

•ΔE = -0.05160 a.u. = -135 kJmol-1

The B-N bond is of dative covalent nature, though there's a strong dipole moment across the bond due to the difference in electronegativity between boron and nitrogen, by comparing to the strength of C-C bond -348 kJmol -1, B-N is a much weaker bond.

===BBr3===

[[File:Figure8dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000018 0.001200 YES </pre>

<pre>Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421
Low frequencies --- 155.9631 155.9651 267.7052 </pre>

Link to log file [[File:DV_BBr3_pseudo_freq_run1.log]]

<jmol><jmolApplet>
<title>BBr3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BBr3_pseudo_freq_run1.log</uploadedFileContents>
</jmolApplet></jmol>

{{DOI|10042/202400}}

==Mini Project==

Isomers of Al2Br2Cl4 were investigated in this section

[[File:Figure9dv.PNG]]

Aluminium and Chlorine atoms optimised with B3LYP/6-31G(d,p) and BR atoms optimised with LanL2DZ pseudopotentials.

===Isomer i (Bridging Br)===

[[File:Figure10dv.PNG]]

Isomer i) energy = -2352.40631 a.u. = -6175067 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000002 0.000300 YES
Maximum Displacement 0.000604 0.001800 YES
RMS Displacement 0.000310 0.001200 YES</pre>

<pre>Low frequencies --- -5.1748 -5.0356 -3.1468 -0.0023 -0.0011 0.0005
Low frequencies --- 14.8260 63.2702 86.0770</pre>

Link to log file [[File:ISO1_AL2BR2CL4_FREQ11.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO1_AL2BR2CL4_FREQ11.LOG</uploadedFileContents>
</jmolApplet></jmol>

===Isomer ii (Bridging Cl with trans terminal Br)===

[[File:Figure11dv.PNG]]

Isomer ii energy = -2352.41630 a.u. = -6175093 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000023 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000863 0.001800 YES
RMS Displacement 0.000319 0.001200 YES</pre>

<pre>Low frequencies --- -4.9721 0.0023 0.0023 0.0027 1.6380 2.3324
Low frequencies --- 18.1768 49.0937 73.0114</pre>

Link to log file [[File:ISO2_AL2BR2CL4_FREQ1.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO2_AL2BR2CL4_FREQ1.LOG</uploadedFileContents>
</jmolApplet></jmol>

•isomer i energy = -6175067 kJmol-1

•isomer ii energy = -6175093 kJmol-1

The second isomer in which there are bridging chlorines instead of bromines is more stable. By considering the orbital overlap and match in energy it is seen that there should be better orbital overlap and match in energy between Al and Cl than between Al and Br because the first two are in the same row in the periodic table, whereas the latter two would lead to more diffuse orbital overlap as Br is in row 4 of the periodic table.

===AlCl2Br===

[[File:Figure17dv.PNG]]

AlCl2Br energy = -1176.19013679 a.u. = -3087499 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000136 0.000450 YES
RMS Force 0.000073 0.000300 YES
Maximum Displacement 0.000760 0.001800 YES
RMS Displacement 0.000497 0.001200 YES
</pre>

<pre> Low frequencies --- 0.0042 0.0049 0.0050 1.3569 3.6367 4.2604
Low frequencies --- 120.5042 133.9178 185.8950 </pre>

Energy of dimer = -6175093 kJmol-1

Energy of AlCl2Br = -3087499 kJmol-1

Dissociation Energy = 2E(monomer) -E(Isomer) = 95 kJmol-1

Link to log file [[File:ALCL2BR_FREQ_RUN3.log]]

<jmol><jmolApplet>
<title>ALCL2BR monomer </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ALCL2BR_FREQ_RUN3.log</uploadedFileContents>
</jmolApplet></jmol>

===MO analysis===

'''MO 40'''

[[File:Figure13dv.PNG]]

Fragment Orbitals

[[File:Figure24dv.PNG]]

[[File:Figure23dv.PNG]]

Interactions

1) medium distance, but s-s orbitals through space antibonding interaction so overall medium antibonding

2) bonding interaction, small distance but p orbitals, so overall strong bonding interaction

3) s-p interaction, short distance, but overlaps out of phase . The terminal orbitals look more like polarised s orbitals than p orbitals. The bonding interactions are outweighed by the antibonding interactions so overall antibonding .

The delocalised pi system prevails in the MO but the other picture on the right shows the nodes on the dimer which also show the MO is overall weakly antibonding̟.

'''MO 48'''

[[File:Figure16dv.PNG]]

Fragment Orbitals

[[File:Figure17dv.PNG]]

The p orbitals on the bridging chlorines here are ignored as are minor contributors to this mo relative to the contributions of the terminal chlorine and bromine p orbitals

''' MO 54'''

[[File:Figure18dv.PNG]]

Fragment Orbitals

[[File:.PNG]]

Rep:Mod:dav16

2018-05-23T13:48:08Z

Dav16: /* MO analysis */

==EX3==
===BH3===

[[File:Dv1.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000009 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000034 0.001800 YES
RMS Displacement 0.000017 0.001200 YES</pre>

<pre>Low frequencies --- -2.2126 -1.0751 -0.0054 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784</pre>

Link to log file [[File:DV_BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

{| class="wikitable" border="1"
|+ CAPTION
! Mode !! Wavenumber /cm-1 !! Intesity/Arbitrary Units!! IR active !! Symmetry !! Vibration Type
|-
| 1 || 1163 || 92 || yes|| A2'''' || out of plane bending
|-
| 2 || 1213 || 14 || yes|| E' || rock bend
|-
| 3 || 1213 || 14|| yes|| E' || rock bend
|-
| 4 || 2582 || 0 || no|| A1' || symmetric stretch(no change in dipole moment)
|-
| 5 || 2715 || 126|| yes|| E' || Asymetric stretch
|-
| 6 || 2715 || 126 || yes|| E' || Asymmetric stretch
|}

[[File:Figure3dv.PNG]]

The obtained computational results there are 6 vibrational modes, it is expected 3 modes following the 3N-6 rule. The spectrum above only shows 3 peaks, modes 2&3 and modes 5&6 have degenerate energy relative to one another, so only appear as one peak in the spectrum. On the other hand, mode 4 corresponds to a symmetric stretch which does not appear in the spectrum because there's no change in dipole moment involved. That gives two peaks so far, such that the remaining peak is due to non-degenerate out of plane bending.

'''MO Analysis'''

[[File:Figure4dv.PNG]]

By comparing the quantified MOs obtained in Gaussian to those expected by applying LCAO, it is seen that the MOs come out as expected in terms of shape and phases. This is a simple MO diagram because there are only 4 atoms involved in a symmetric arrangement in an 8 electron system. It is seen that for the higher energy MOs the electron density is more diffuse and the shape of the MOs becomes harder to interpret relative to the MOs expected from theory.

===NH3===

[[File:Figure5dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000092 0.000450 YES
RMS Force 0.000039 0.000300 YES
Maximum Displacement 0.000304 0.001800 YES
RMS Displacement 0.000101 0.001200 YES </pre>

<pre> Low frequencies --- -32.4128 -32.3999 -11.4544 -0.0040 0.0076 0.0521
Low frequencies --- 1088.7642 1694.0248 1694.0252 </pre>

Link to log file [[File:DV_NH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

===NH3BH3===

[[File:Figure7dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000114 0.000450 YES
RMS Force 0.000063 0.000300 YES
Maximum Displacement 0.000621 0.001800 YES
RMS Displacement 0.000355 0.001200 YES</pre>

<pre>Low frequencies --- -0.0617 -0.0457 -0.0067 21.6783 21.6842 40.5400
Low frequencies --- 266.0169 632.3610 640.1360 </pre>

Link to log file [[File:DV_NH3BH3_FREQ.LOG]]

<jmol><jmolApplet>
<title>NH3BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_NH3BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

•E(NH3)= -56.55777 a.u.

•E(BH3)= -26.61532 a.u.

•E(NH3BH3)= -83.22469 a.u.

•ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22469 - (-26.61532-56.55777)

•ΔE = -0.05160 a.u. = -135 kJmol-1

The B-N bond is of dative covalent nature, though there's a strong dipole moment across the bond due to the difference in electronegativity between boron and nitrogen, by comparing to the strength of C-C bond -348 kJmol -1, B-N is a much weaker bond.

===BBr3===

[[File:Figure8dv.PNG]]

<pre> Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000018 0.001200 YES </pre>

<pre>Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421
Low frequencies --- 155.9631 155.9651 267.7052 </pre>

Link to log file [[File:DV_BBr3_pseudo_freq_run1.log]]

<jmol><jmolApplet>
<title>BBr3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>DV_BBr3_pseudo_freq_run1.log</uploadedFileContents>
</jmolApplet></jmol>

{{DOI|10042/202400}}

==Mini Project==

Isomers of Al2Br2Cl4 were investigated in this section

[[File:Figure9dv.PNG]]

Aluminium and Chlorine atoms optimised with B3LYP/6-31G(d,p) and BR atoms optimised with LanL2DZ pseudopotentials.

===Isomer i (Bridging Br)===

[[File:Figure10dv.PNG]]

Isomer i) energy = -2352.40631 a.u. = -6175067 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000002 0.000300 YES
Maximum Displacement 0.000604 0.001800 YES
RMS Displacement 0.000310 0.001200 YES</pre>

<pre>Low frequencies --- -5.1748 -5.0356 -3.1468 -0.0023 -0.0011 0.0005
Low frequencies --- 14.8260 63.2702 86.0770</pre>

Link to log file [[File:ISO1_AL2BR2CL4_FREQ11.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO1_AL2BR2CL4_FREQ11.LOG</uploadedFileContents>
</jmolApplet></jmol>

===Isomer ii (Bridging Cl with trans terminal Br)===

[[File:Figure11dv.PNG]]

Isomer ii energy = -2352.41630 a.u. = -6175093 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000023 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000863 0.001800 YES
RMS Displacement 0.000319 0.001200 YES</pre>

<pre>Low frequencies --- -4.9721 0.0023 0.0023 0.0027 1.6380 2.3324
Low frequencies --- 18.1768 49.0937 73.0114</pre>

Link to log file [[File:ISO2_AL2BR2CL4_FREQ1.LOG]]

<jmol><jmolApplet>
<title>AL2BR2CL4 Isomer i)</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ISO2_AL2BR2CL4_FREQ1.LOG</uploadedFileContents>
</jmolApplet></jmol>

•isomer i energy = -6175067 kJmol-1

•isomer ii energy = -6175093 kJmol-1

The second isomer in which there are bridging chlorines instead of bromines is more stable. By considering the orbital overlap and match in energy it is seen that there should be better orbital overlap and match in energy between Al and Cl than between Al and Br because the first two are in the same row in the periodic table, whereas the latter two would lead to more diffuse orbital overlap as Br is in row 4 of the periodic table.

===AlCl2Br===

[[File:Figure17dv.PNG]]

AlCl2Br energy = -1176.19013679 a.u. = -3087499 kJmol-1

<pre> Item Value Threshold Converged?
Maximum Force 0.000136 0.000450 YES
RMS Force 0.000073 0.000300 YES
Maximum Displacement 0.000760 0.001800 YES
RMS Displacement 0.000497 0.001200 YES
</pre>

<pre> Low frequencies --- 0.0042 0.0049 0.0050 1.3569 3.6367 4.2604
Low frequencies --- 120.5042 133.9178 185.8950 </pre>

Energy of dimer = -6175093 kJmol-1

Energy of AlCl2Br = -3087499 kJmol-1

Dissociation Energy = 2E(monomer) -E(Isomer) = 95 kJmol-1

Link to log file [[File:ALCL2BR_FREQ_RUN3.log]]

<jmol><jmolApplet>
<title>ALCL2BR monomer </title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ALCL2BR_FREQ_RUN3.log</uploadedFileContents>
</jmolApplet></jmol>

===MO analysis===

'''MO 40'''

[[File:Figure13dv.PNG]]

Fragment Orbitals

[[File:Figure22dv.PNG]]

[[File:Figure23dv.PNG]]

Interactions

1) medium distance, but s-s orbitals through space antibonding interaction so overall medium antibonding

2) bonding interaction, small distance but p orbitals, so overall strong bonding interaction

3) s-p interaction, short distance, but overlaps out of phase . The terminal orbitals look more like polarised s orbitals than p orbitals. The bonding interactions are outweighed by the antibonding interactions so overall antibonding .

The delocalised pi system prevails in the MO but the other picture on the right shows the nodes on the dimer which also show the MO is overall weakly antibonding̟.

'''MO 48'''

[[File:Figure16dv.PNG]]

Fragment Orbitals

[[File:Figure17dv.PNG]]

The p orbitals on the bridging chlorines here are ignored as are minor contributors to this mo relative to the contributions of the terminal chlorine and bromine p orbitals

''' MO 54'''

[[File:Figure18dv.PNG]]

Fragment Orbitals

[[File:.PNG]]