File:Vg3217 t2g.bmp

2019-05-20T14:56:01Z

Vg3217:

File:Vg3217 eg.bmp

2019-05-20T14:55:46Z

Vg3217:

File:Vg3217 a1g.bmp

2019-05-20T14:55:22Z

Vg3217:

2019-05-20T12:50:34Z

Vg3217: /* Comparative analysis */

Vg3217 inorg2ndyear

2019-05-20T12:39:33Z

Vg3217: /* Part II */

= BH3 optimisation =

Method: B3YLP

Basis set: 6-31G (d,p)

[[File:Vg3217_bh3_opt.PNG|thumb|none|Gaussview summary table of an optimised BH3 molecule]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000011 0.000450 YES
RMS Force 0.000007 0.000300 YES
Maximum Displacement 0.000043 0.001800 YES
RMS Displacement 0.000028 0.001200 YES
Predicted change in Energy=-6.942915D-10
Optimization completed.
-- Stationary point found.
</pre>

[[Media:BH3_631GDP_FREQ.LOG|Frequency calculation log file]]

<pre>
Low frequencies --- -14.6858 -14.6818 -11.0436 0.0010 0.0165 0.3415
Low frequencies --- 1162.9492 1213.1220 1213.1222
</pre>

<jmol><jmolApplet>
<title>Optimised BH3 molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>BH3_631GDP_FREQ.LOG</uploadedFileContents>
<script>frame x.y</script>
</jmolApplet></jmol>

{| class="wikitable"
|+
|-
|wavenumber (cm-1) || Intensity (arbitrary units) || symmetry || IR active || type
|-
| 2716
| 126
| E'
| yes
| asymmetric stretch
|-
| 2716
| 126
| E'
| yes
| asymmetric stretch
|-
| 2583
| 0
| A1'
| no
| symmetric stretch
|-
| 1213
| 14
| E'
| yes - weak
| angle deformation
|-
| 1213
| 14
| E'
| yes - weak
| angle deformation
|-
| 1163
| 93
| E'
| yes
| umbrella
|}

[[File:Vg3217_bh3_spec.png|thumb|none|Predicted BH3 IR spectrum]]

The symmetrical stretch does not lead to a change in dipole moment and so is not visibile in IR. The asymmetrical stretches and angle deformations are each degenerate, resulting in one peak for each mode.

[[File:Vg3217_bh3_mo.bmp|thumb|none|MO diagram of BH3]]

The MOs obtained through LCAOs closely match the ones predicted by Gaussian. Therefore, MO theory can reliably provide useful information on relative energy levels and bonding character.

=NH3=

Method: B3YLP

Basis set: 6-31G (d,p)

[[File:Vg3217_nh3_opt.PNG|thumb|none|Gaussview summary table of an optimised NH3 molecule]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000012 0.001800 YES
RMS Displacement 0.000008 0.001200 YES
Predicted change in Energy=-9.843795D-11
Optimization completed.
-- Stationary point found.
</pre>

[[Media:vg3217_NH3_631GDP_FREQ.LOG|Frequency calculation log file]]

<pre>
Low frequencies --- -0.0140 -0.0032 -0.0015 7.0783 8.0932 8.0937
Low frequencies --- 1089.3840 1693.9368 1693.9368
</pre>

<jmol><jmolApplet>
<title>Optimised NH3 molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>vg3217_NH3_631GDP_FREQ.LOG</uploadedFileContents>
<script>frame x.y</script>
</jmolApplet></jmol>

=H3NBH3=

Method: B3YLP

Basis set: 6-31G (d,p)

[[File:Vg3217_h3nbh3_opt.PNG|thumb|none|Gaussview summary table of an optimised H3NBH3 molecule]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000122 0.000450 YES
RMS Force 0.000058 0.000300 YES
Maximum Displacement 0.000531 0.001800 YES
RMS Displacement 0.000296 0.001200 YES
Predicted change in Energy=-1.655945D-07
Optimization completed.
-- Stationary point found.
</pre>

[[Media:vg3217_H3NBH3_631GDP_FREQ.LOG|Frequency calculation log file]]

<pre>
Low frequencies --- -0.0251 -0.0030 0.0011 17.1236 17.1258 37.1326
Low frequencies --- 265.7816 632.2034 639.3483
</pre>

<jmol><jmolApplet>
<title>Optimised NH3 molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>vg3217_H3NBH3_631GDP_FREQ.LOG</uploadedFileContents>
<script>frame x.y</script>
</jmolApplet></jmol>

1 Eh= 2625.50 kJ mol -1

5 kJ mol -1 = 0.002 Eh

E(NH3) = -26.615 Eh

E(BH3) = -56.558 Eh

E(H3NBH3) = -83.225 Eh

<math>\Delta</math>E = E(H3NBH3) - [ E(NH3) + E(BH3) ] = -0.052 Eh = -140 kJ/mol

The dative N-B bond has less than half the energy of the covalent N-B bond (389 kJ/mol), making it very weak in comparison.

=NI3=
Method: B3YLP

Basis sets:
* N: 6-31G (d,p)
* I: LanL2DZ

[[File:Vg3217_ni3_opt.PNG|thumb|none|Gaussview summary table of an optimised NI3 molecule]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000065 0.000450 YES
RMS Force 0.000038 0.000300 YES
Maximum Displacement 0.000952 0.001800 YES
RMS Displacement 0.000415 0.001200 YES
Predicted change in Energy=-5.172366D-08
Optimization completed.
-- Stationary point found.
</pre>

[[Media:Vg3217_NI3_GEN_SYM_OPT_FREQ_LOCAL.LOG|Frequency calculation log file]]

<pre>
Low frequencies --- -0.1614 -0.0983 -0.0031 0.5823 0.7024 1.5522
Low frequencies --- 101.3248 101.3255 148.3662
</pre>

<jmol><jmolApplet>
<title>Optimised NI3 molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>Vg3217_NI3_GEN_SYM_OPT_FREQ_LOCAL.LOG</uploadedFileContents>
<script>frame x.y</script>
</jmolApplet></jmol>

Optimised N-I bond length: 2.18 x 10-10m

2019-05-16T13:53:26Z

Vg3217: