ICC2 01053372

2018-05-25T12:03:43Z

Jnl115: /* MO Analysis */

===EX3 Section===

====BH3====
''Method & Basis Set''

RB3LYP

6-31G(d,p)

''Summary Table''
[[File:01053372_BH3_OPT_II_Summary_II.JPG|thumb|center]]

''Item Table''
<pre>
Item Value Threshold Converged?
Maximum Force 0.000006 0.000450 YES
RMS Force 0.000004 0.000300 YES
Maximum Displacement 0.000022 0.001800 YES
RMS Displacement 0.000015 0.001200 YES
Predicted change in Energy=-1.868217D-10
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

[[Media:JNL_BH3_FREQ_01053372.LOG|BH3 Frequency .log]]

''Low Frequency Analysis''
<pre>
Low frequencies --- -2.2126 -1.0751 -0.0055 2.2359 10.2633 10.3194
Low frequencies --- 1162.9860 1213.1757 1213.1784
</pre>

''Frequency Table''
{| class="wikitable"
|+
|-
|wavenumber (cm-1 || Intensity (arbitrary units) || symmetry || IR active? || type
|-
|1163
|93
|A2
|yes
|out-of-plane bend
|-
|1213
|14
|E
|yes
|bend
|-
|1213
|14
|E
|yes
|bend
|-
|2582
|0
|A1
|no
|symmetric stretch
|-
|2700
|126
|E
|yes
|asymmetric stretch
|-
|2715
|126
|E
|yes
|asymmetric stretch
|}

''IR Spectrum''
[[File:BH3 OPT II Freq IR01053372.JPG|thumb|center|BH3 Calculated IR Spectrum]]

There are only 3 peaks produced from 6 different vibrations. This can be explained by the fact that two pairs degenerate vibrations (the vibrations at 2700cm*-1, and the vibrations at 1200 cm*-1) which will each produce only one IR peak, as they abosrb at the same energy. Also the vibration at 2600cm*-1 is symmetric and therefore IR inactive, it does not absorb IR radiation. This reduces the 6 vibrations to only 3 observed peaks

''MO Diagram''
[[File:BH3 MO DiagramI01053372.png|thumb|center]]

''Dynamic Image''

<jmol><jmolApplet>
<title>BH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>JNL_BH3_FREQ_01053372.LOG</uploadedFileContents>
</jmolApplet></jmol>

====NH3====

''Method & Basis Set''

RB3LYP

6-31G(d,p)

''Summary Table''
[[File:JNL NH3 Summary 01053372.PNG|thumb|center]]

''Item Table''
<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=-9.843916D-11
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

[[Media:JNL NH3 FREQ 01053372.LOG|NH3 Frequency .log]]

''Low Frequency Analysis''
<pre>
Low frequencies --- -8.5646 -8.5588 -0.0044 0.0454 0.1784 26.4183
Low frequencies --- 1089.7603 1694.1865 1694.1865
</pre>

''Dynamic Image''

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>JNL NH3 FREQ 01053372.LOG</uploadedFileContents>
</jmolApplet></jmol>

====NH3BH3====

''Method & Basis Set''

RB3LYP

6-31G(d,p)

''Summary Table''
[[File:JNL NH3BH3 Summary 01053372.PNG |thumb|center]]

''Item Table''
<pre>
Item Value Threshold Converged?
Maximum Force 0.000123 0.000450 YES
RMS Force 0.000058 0.000300 YES
Maximum Displacement 0.000515 0.001800 YES
RMS Displacement 0.000296 0.001200 YES
Predicted change in Energy=-1.635696D-07
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

[[Media:JNL_NH3BH3_FREQ_01053372.LOG|NH3BH3 Frequency .log]]

''Low Frequency Analysis''
<pre>
Low frequencies --- -0.0007 0.0004 0.0015 18.3844 27.7829 40.0656
Low frequencies --- 266.4161 632.3928 639.8576
</pre>

''Dynamic Image''

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>JNL_NH3BH3_FREQ_01053372.LOG</uploadedFileContents>
</jmolApplet></jmol>

====ΔE====

E(NH3)= -26.615 a.u

E(BH3)= -56.558 a.u

E(NH3BH3)= -83.225 a.u

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -0.052 a.u ≈ 137 kJ/mol

''Q:'' Based on your energy calculation is the B-N dative bond weak, medium or strong? What comparison have you made to come to this conclusion?

B-N Bond dissociation energy is 377.9 ± 8.7
*Ref_http://staff.ustc.edu.cn/~luo971/2010-91-CRC-BDEs-Tables.pdf
Therefore the B-N dative bond is weak compared to a diatomic B-N bond.

====BBr3====

''Method & Basis Set''

B3LYP

''B:''
6-31G(d,p)

''Br:''
LANL2DZ

''Summary Table''
[[File:JNL_BBR3_Summary_01053372.PNG|thumb|center]]

''Item Table''
<pre>
Item Value Threshold Converged?
Maximum Force 0.000008 0.000450 YES
RMS Force 0.000005 0.000300 YES
Maximum Displacement 0.000036 0.001800 YES
RMS Displacement 0.000023 0.001200 YES
Predicted change in Energy=-4.026880D-10
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

{{DOI|10042/202455}}

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

''Dynamic Image''

<jmol><jmolApplet>
<title>NH3</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>JNL_BBR3_SCANFREQ_01053372.log</uploadedFileContents>
</jmolApplet></jmol>

===Project===

====Benzene====

''Method & Basis Set''

B3LYP
6-31G (d,p)

''Summary Table''
[[File:JNL_BENZ_Summary.PNG|thumb|center]]

''Item Table''
<pre>
Item Value Threshold Converged?
Maximum Force 0.000193 0.000450 YES
RMS Force 0.000079 0.000300 YES
Maximum Displacement 0.000830 0.001800 YES
RMS Displacement 0.000294 0.001200 YES
Predicted change in Energy=-4.437902D-07
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

[[Media:JNL_BENZ_FREQ.LOG|benzene Frequency .log]]

''Low Frequencies''
<pre>
Low frequencies --- -17.2053 -14.9372 -14.9372 -0.0054 -0.0054 0.0005
Low frequencies --- 414.1053 414.1053 620.9426
</pre>

''Dynamic Image''

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

====Borazine====

B3LYP
6-31G (d,p)

''Summary Table''
[[File:JNL_BORAZ_Summary.PNG|thumb|center]]

''Item Table''

<pre>
Item Value Threshold Converged?
Maximum Force 0.000085 0.000450 YES
RMS Force 0.000033 0.000300 YES
Maximum Displacement 0.000250 0.001800 YES
RMS Displacement 0.000075 0.001200 YES
Predicted change in Energy=-9.266551D-08
Optimization completed.
-- Stationary point found.
</pre>

''Frequency .log File''

[[Media:JNL_BORAZ_FREQ.LOG|Borazine Frequency .log]]

''Low Frequencies''
<pre>
Low frequencies --- 0.0004 0.0008 0.0012 3.4393 4.3291 6.8386
Low frequencies --- 289.7037 289.7792 404.4212
</pre>

''Dynamic Image''

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

====Charge Analysis====

[[File:JNL_PTE_Electronegativity.PNG]]
*Ref:https://en.wikipedia.org/wiki/Electronegativity

{| class="wikitable" border="1"
|+ Charge Analysis
! Molecule !! Comparison Charge Colour Diagram !! Charge Values !! Comment
|-
| Benzene || [[File:JNL_BENZ_Charge.PNG|thumb|center]] || '''C'''=-0.239 '''H'''=0.239 || Seeing as Carbon and Hydrogen have similar electronegativity values, 2.55 & 2.20 respectively, the bonds are not very polarized and mostly display covalent character. Therefore carbon will only carry a little more electron density than Hydrogen, as it is slightly more electronegative. This can be seen on the charge analysis where both Carbon and Hydrogen atoms are a dark shade of red or green, representing a small charge of -0.239 and 0.239 on each atom respectively.
|-
| Borazine || [[File:JNL_BORAZ_Charge.PNG|thumb|center]] || '''N'''=-1.102 '''H'''=0.432 '''B'''=0.747 '''H'''=-0.077 || On the other hand in Borazine, the Nitrogen atoms are much more electronegative than the Hydrogen atoms, with a Pauling electronegativity of 3.04 compared to 2.20. Therefore the nitrogen Hydrogen bond is quite polarized resulting in an electron rich Nitrogen and an electron deficient Hydrogen. This can be seen in the Charge-Colour Diagram where the Nitrogen atoms are a bright shade of red, representing a charge of -1.102, and the Hydrogen's attached to them are a bright green colour (compared to the dark B-H hydrogens, or C-H hydrogens found in Benzene), representing a high positive charge of 0.432.
The Boron atoms are ''less'' electronegative compared to Hydrogen. This results in a reversal of charges that we previously saw in benzene C-H and Borazine N-H bonds. The Hydrogen is represented as black in the charge colour diagram, due to it's small negative charge of -0.077 *?units, and the Boron is represented as a light green colour due to it's 0.747 positive charge.
|}

====MO Analysis====

{| class="wikitable" border="1"
|+ MO Analysis
! Energy Level !! Benzene !! Borazine !! Comment
|-
| '''Benzene:'''21 '''Borazine:'''20 || [[File:JNL_BENZ_MO21.PNG|300px]] || [[File:JNL_BORAZ_MO20.PNG|300px]] || The MO displayed here is the HOMO for Benzene, however it was found at one energy level below the HOMO in Borazine. It can be classified as a π-bonding MO since a rotation of 180 degrees about the internuclear axis will result in a change of sign. The overall character of the MO is bonding due to the in phase contributions below and above the nodal plane through the middle of the molecule, however this nodal plane is an anti-bonding contribution to the MO, and is quite significant as it is internuclear. The contributing atomic orbitals in both cases are pz orbitals of the same phase on the bottom half of the molecule, and pz orbitals of the opposite phase on the top half.
|-
| 17 || [[File:JNL_BENZ_MO17.PNG|300px]] || [[File:JNL_BORAZ_MO17.PNG|300px]] || This MO was found at Energy Level 17 for both Benzene and Borazine, and is basically identical for both systems. It can be classified as a π-bonding MO since a rotation of 180 degrees about the internuclear axis will result in a change of sign. It is in fact the first and most symmetrical π-bonding MO, giving it a strong bonding character due to the all in phase AO interactions. The contributing AO's are the same phase pz orbitals on each atom in the hexagonal ring.
|-
| 13/15 || [[File:JNL_BENZ_MO15.PNG|thumb|center]] || [[File:JNL_BORAZ_MO13.PNG|thumb|center]] ||
|}

====Aromaticity====

The structure of Benzene, the archetypal aromatic molecule, was deduced from 3 main pieces of evidence:
Bond Length/X Ray Diffraction
Energy of Hydrogenation
NMR H Values
Valence Bond Theory of Aromaticity (single/double bonds)

MO Theory
Huckles Rules

Paper (Why overlapping PZ is not good description)

https://www.imperial.ac.uk/media/imperial-college/research-centres-and-groups/spivey-group/teaching/org1aromatics/lecture11718.pdf
https://en.wikipedia.org/wiki/Aromaticity

ICC2 01053372

2018-05-25T11:57:56Z

2018-05-24T17:47:29Z

Jnl115: /* Aromaticity */