User:Lmf12

Chemical Bonding

A bond is considered to have been formed between two atoms when the energy of the individual atoms are higher than that of molecule. The bond length is a result of attractive and repulsive forces between the nuclei and the electrons of the two atoms that reaches an energy minimum. From looking at a plot of potential energy vs. internuclear distance it can be seen that a shortening of the bond would result in an increase in energy - this is due to repulsion forces between the two nuclei and between their electrons. However, a lengthening of the bond would result in an increase in attractive forces bringing the two nuclei closer together.^[1]

The bond energy can be used to measure the strength of a bond and is defined as how much energy that is required to break one mole of molecules into their individual atoms.^[3]. A strong bond would be the N≡N bond that has a bond energy of 946 kJ/mol, a bond of medium strength would be Si-O that has a bond energy of 460 kJ/mol and a weak bond would be a C-1 bond that has a bond energy of 213 kJ/mol^[4].

Bonding in MX₃ and MH₃ Species

Geometry data
	BH₃	BBr₃	GaBr₃
r(E-X)	1.19	1.93	2.35
θ(X-E-X)	120.0	120.0	120.0

From looking at the geometrical data for the cases listed above it can be seen that substituting the H atoms in BH₃ with Br atoms increases the bond length. This is expected as Br is in Period 4 (compared to H in Period 1) and therefor sterically larger than H, resulting in a longer bond. From substituting the Boron atom with Gallium, that is found in the same group but in Period 4 the bond distance increases further. All these molecules will take a trigonal planar form, and thus have the same bond angles.

However, it is found experimentally that the bonds in MX₃ species of Group 13 are shorter than what would be expected from looking at the covalent radii of the individual atoms in combination with the ionic contribution to the bonds.^[5]. This is due to an effect referred to as π-bonding, where the halide donates electron density to the electron deficient central metal atom through low lying energy p-orbitals, which results in a shortening of the bond (compared to purely the covalent radii). In BH₃ species the electron 'donation' from H is purely inductive through the σ-bond since there are no filled p-orbitals on H that can interact with the empty p-orbital on Boron.

This overlap is greatest for p-orbitals of similar size, as it allows a better energy match. however, as the orbital size increases further down a group, it also becomes more diffuse. In order to determine which effect that contributes the most to the bond strength, calculations were carried out using B3LYP/6-31G for BH₃ and NH₃ and B3LYP/LANL2DZ for GaBr₃ and BBr₃.

The energies found were:

E(BH₃)=-26.62 a.u. E(NH₃)=-56.55 a.u. E(GaBr₃)=-41.70 a.u. E(BBr₃)=-64.44 a.u.

This indicates that the NH₃ bond is stronger than the BH₃ bonds and that the BBr₃ bond is stronger than the GaBr₃ bond.

For BBr₃, the 2p(B)-4p(Br) orbital overlap is better and therefor the bond is stronger whereas for GaBr₃, the 4p(Ga)-4p(B) orbital overlap, although providing a better energy energy match, are between two diffuse orbitals and the atoms are sterically large, so the bond will be weaker and hence easier to break.

Software: Gauss View

Using programmes such as Gauss View can sometimes be misleading; Gauss view draw bonds based on a distance criteria and if the distance exceeds this pre-defined value Gauss View will not recognise that there is a bond present. However, this does not mean that the bond does not exist.

When a frequency analysis is carried out using Gauss View, the software has taken the second derivative of the potential energy surface of a molecule. This means that if the frequencies are all positive there is a minimum, if one of them should be negative a transition state has been located and if more than one is negative then the critical point was not find, this means that either the optimisation was not completed or failed.

BH₃ Project Section

BH₃ Optimisation Data

B3LYP/3-21G level

Optimisation log file here

summary data

convergence

Jmol

   Item               Value     Threshold  Converged?
 Maximum Force            0.000217     0.000450     YES
 RMS     Force            0.000105     0.000300     YES
 Maximum Displacement     0.000919     0.001800     YES
 RMS     Displacement     0.000441     0.001200     YES
 Predicted change in Energy=-1.635268D-07
 Optimization completed.

optimised BH3 molecule

B3LYP/6-31G level

Optimisation log file here

summary data

convergence

Jmol

Item               Value     Threshold  Converged?
 Maximum Force            0.000012     0.000450     YES
 RMS     Force            0.000008     0.000300     YES
 Maximum Displacement     0.000064     0.001800     YES
 RMS     Displacement     0.000039     0.001200     YES
 Predicted change in Energy=-1.126784D-09
 Optimization completed.

optimised BH3 molecule

BH₃ Symmetry

Optimisation log file here


summary data	low modes
	Full mass-weighted force constant matrix: Low frequencies --- -14.5183 -14.5142 -10.8197 -0.0005 0.0169 0.3454 Low frequencies --- 1162.9508 1213.1230 1213.1232

Vibrational spectrum for BH₃


Wavenumber	Intensity	IR active?	Type	IR Spectrum
1162.95	92.5706	yes	bend
1213.12	14.0539	very slight	bend
1213.12	14.0539	very slight	bend
2582.66	0.0000	no	symmetric stretch
2715.81	126.3291	no	asymmetric stretch
2715.81	126.3291	no	asymmetric stretch

As can be seen from the Ir spectrum there are two regions of IR-active modes; one at ≈1200 cm-1 and one at ≈2600-2700cm-1. The lower frequency region comes from the asymmetrical bending modes of the molecule, and are of lower frequency as less energy is required to bend a bond than to stretch it.

Molecular Orbital Diagram for BH₃

Where the Linear Compination of Atomic Orbitals (LCAO) approximation has been used the electrons are more localised whereas for the real molecular orbitals the electrons delocalise over the entire molecule. The LCAO approximation is still very useful when it comes to estimating energy levels, but can give the wrong order of orbitals that are very close in energy.

GaBr₃ Project Section

GaBr₃ Optimisation Data

DOI:10042/31149

B3LYP/LANL2ZD level

Optimisation log file here

summary data

convergence

Jmol

  Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000450     YES
 RMS     Force            0.000000     0.000300     YES
 Maximum Displacement     0.000003     0.001800     YES
 RMS     Displacement     0.000002     0.001200     YES
 Predicted change in Energy=-1.307747D-12
 Optimization completed.

optimised GaBr3 molecule

GaBr₃ Symmetry

Optimisation log file here


summary data	low modes
	Full mass-weighted force constant matrix: Low frequencies --- -1.4878 -0.0015 -0.0002 0.0096 0.6540 0.6540 Low frequencies --- 76.3920 76.3924 99.6767

Vibrational spectrum for GaBr₃


Wavenumber	Intensity	IR active?	Type	IR Spectrum
76.39	3.3451	yes	bend
76.39	3.3450	very slight	bend
99.68	9.2166	very slight	bend
197.33	0.0000	no	symmetric stretch
316.18	57.0655	no	asymmetric stretch
316.18	57.0669	no	asymmetric stretch

Comparing this spectrum to that of BH3 they look very similar which is due to that they both belong to the same point group. The asymmetric stretch occurs at a significantly lower frequency which is due to that the GaBr3 is much larger in size and the bonding present is weaker.

BBr₃ Project Section

DOI:10042/31164

B3LYP/Gen level

Optimisation log file here

summary data

convergence

Jmol

 Item               Value     Threshold  Converged?
 Maximum Force            0.000013     0.000450     YES
 RMS     Force            0.000006     0.000300     YES
 Maximum Displacement     0.000058     0.001800     YES
 RMS     Displacement     0.000029     0.001200     YES
 Predicted change in Energy=-6.008434D-10
 Optimization completed.

optimised BBr3 molecule

NH₃ Project Section

NH₃ Optimisation Data

B3LYP/6-31G level

Optimisation log file here

summary data

convergence

Jmol

  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=-9.843885D-11
 Optimization completed.

optimised BH3 molecule

NH₃ Symmetry

Optimisation log file here


summary data	low modes
	Full mass-weighted force constant matrix: Low frequencies --- -0.0138 -0.0026 -0.0009 7.0783 8.0932 8.0937 Low frequencies --- 1089.3840 1693.9368 1693.9368

Vibrational spectrum for NH₃


Wavenumber	Intensity	IR active?	Type	IR Spectrum
1089.16	145.4750	yes	bend
1693.89	13.5595	very slight	bend
1693.90	13.5628	very slight	bend
3461.54	1.0576	no	stretch
3590.00	0.2684	no	asymmetrical stretch
3590.24	0.2686	no	asymmetrical stretch

From comparing the NH3 spectrum with that of BH3 and GaBr3 it looks a bit difference. This is partly due to the presence of an electron lone pair on Nitrogen.

Umbrella modes

By looking at the so called umbrella modes for the GaBr3 and the BH3 molecule one important difference can be spotted. This is that in the GaBr3 the Gallium is what is moving up and down as it is the lightest atom in the molecule. For BH3 this species would be H and so these are the ones that are moving.

NBO Analysis/Charge Distribution


Charge Distribution	Specific NBO Charges for N and H	Display Charge Distribution

From looking at the picture above it can be seen that the charge distribution is as would be expected from the relative electronegativities of the individual atoms, where the negative charge is on the Nitrogen and the positive charge is on the Hydrogen atoms, suggesting that there is an ionic contribution to the bonding present in the NH3 species.

Ammonia-Borane NH₃BH₃ Project Section

NH₃ BH₃ Optimisation Data

B3LYP/6-31G level

Optimisation log file here

summary data

convergence

Jmol

 Item               Value     Threshold  Converged?
 Maximum Force            0.000121     0.000450     YES
 RMS     Force            0.000057     0.000300     YES
 Maximum Displacement     0.000507     0.001800     YES
 RMS     Displacement     0.000295     0.001200     YES
 Predicted change in Energy=-1.613117D-07
 Optimization completed.

optimised NH3BH3 molecule

NH₃BH₃ Symmetry

Optimisation log file here


summary data	low modes
	Full mass-weighted force constant matrix: Low frequencies --- -0.1450 -0.0736 -0.0066 13.3607 13.3703 15.4061 Low frequencies --- 263.5321 633.1134 639.2469

Vibrational spectrum for BH₃NH₃


Wavenumber	Intensity	IR active?	Type
263.52	0.0000	yes	bend
633.11	13.9670	very slight	bend
639.25	3.5366	very slight	bend
639.25	3.5342	no	stretch
1069.30	40.5370	no	stretch
1069.30	40.5392	no	stretch
1196.45	108.9089	no	stretch
1203.37	3.4661	no	stretch
1203.37	3.4667	no	stretch
1329.59	113.7238	no	stretch
1676.44	27.5513	no	stretch
1676.44	27.5515	no	stretch
2472.01	67.2562	no	stretch
2532.19	231.2574	no	stretch
2532.19	231.2328	no	stretch
3463.99	2.5114	no	stretch
3580.97	27.9581	no	stretch
3580.97	27.9582	no	stretch

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]

ΔE=-83.22468892-[(-56.55776872 a.u.)+(-26.61532364 a.u.)]= -0.05159656 a.u.

ΔE=-135.4672842 J/mol

Al₂Cl₂Br₂ Lab Project Section

The Different Isomers of Al₂Cl₂Br₂

Al₂Cl₂Br₂ can form five different isomers, all shown in the picture with their respective point groups.

B3LYP/6-31G level, Isomer 1

Optimisation log file here

summary data

convergence

Jmol

  Item               Value     Threshold  Converged?
 Maximum Force            0.000003     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000057     0.001800     YES
 RMS     Displacement     0.000015     0.001200     YES
 Predicted change in Energy=-2.941232D-10
 Optimization completed.

optimised BH3 molecule

Al₂Cl₂Br₂ Isomer 1 Symmetry

Optimisation log file here


summary data	low modes
	Low frequencies --- -5.1748 -5.0352 -3.1463 0.0014 0.0018 0.0020 Low frequencies --- 14.8261 63.2702 86.0770

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 1


Mode	Frequency	Intensity	Type
1	14.83	0.3441	Al-Br bend
5	107.58	4.5739	Al-Cl bend
7	125.65	8.1417	Al-Cl bend
9	138.38	7.0416	Al-Br bend
12	240.99	99.7791	Al-Br stretch
14	341.30	160.6480	Al-Br stretch
15	467.23	346.5463	Cl-Al-Br Stretch
18	616.34	331.8044	Al-Cl stretch

|

B3LYP/6-31G level, Isomer 2

Optimisation log file here

summary data

convergence

Jmol

  Item               Value     Threshold  Converged?
 Maximum Force            0.000105     0.000450     YES
 RMS     Force            0.000026     0.000300     YES
 Maximum Displacement     0.001357     0.001800     YES
 RMS     Displacement     0.000596     0.001200     YES
 Predicted change in Energy=-1.134244D-07
 Optimization completed.

optimised BH3 molecule

Al₂Cl₂Br₂ Isomer 2 Symmetry

Optimisation log file here


summary data	low modes
	Low frequencies --- -2.9931 -1.4948 -0.0035 -0.0026 0.0015 3.0891 Low frequencies --- 17.0169 55.9580 80.0480

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 2


Mode	Frequency	Intensity	Type
1	17.01	0.3958	Al-Br/Al-Cl stretch
6	109.63	5.1468	Al-Cl bend
7	121.15	7.5623	Al-Cl/Al-Br bend
8	148.92	5.1319	Al-Cl bend
9	154.30	6.2886	Al-Br/Al-Cl bend
11	211.10	21.1007	Al-Br stretch
12	257.45	9.6920	Al-Br/Al-Cl (bridging)
13	289.07	47.9373	Al-Cl stretch (bridging)
14	384.41	153.7854	Al-Cl stretch (bridging)
15	424.13	274.3499	Al-Cl stretch (bridging)
16	492.85	106.5828	Al-Cl stretch (bridging)
17	574.48	121.8889	Al-Cl stretch (terminal)
18	614.55	197.1619	Al-Cl stretch (terminal)

|

This is where you add your explanation of why there are fewer vibrational peaks than there are vibrations.(Because some of the energy levels are degenerate and so give rise to only one peak in the spectrum.

B3LYP/6-31G level, Isomer 3

Optimisation log file here

summary data

convergence

Jmol

  Item               Value     Threshold  Converged?
 Maximum Force            0.000120     0.000450     YES
 RMS     Force            0.000043     0.000300     YES
 Maximum Displacement     0.000153     0.001800     YES
 RMS     Displacement     0.000049     0.001200     YES
 Predicted change in Energy=-1.401356D-08
 Optimization completed.

optimised BH3 molecule

Al₂Cl₂Br₂ Isomer 3 Symmetry

Optimisation log file here


summary data	low modes
	Low frequencies --- -4.1720 -2.6762 -1.2823 -0.0029 -0.0025 -0.0025 Low frequencies --- 17.8116 50.9340 72.1836

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 3


Mode	Frequency	Intensity	Type
1	17.81	0.4847	Al-Cl bend
3	72.18	0.5506	Al-Br/Al-Cl bend bend (terminal)
6	111.94	7.5673	Al-Br/Al-Cl bend bend (terminal)
8	159.74	1.2083	Al-Cl bend
9	165.82	6.5596	Al-Cl bend (terminal + bridging)
10	186.75	1.6215	Al-Cl bend
12	270.91	13.3026	Al-Br/Al-Cl stretch (bridging)
13	322.43	41.4391	Al-Cl stretch (bridging)
14	413.35	149.5130	Al-Cl stretch (bridging)
15	419.11	310.3169	Al-Br/Al-Cl stretch (bridging)
16	495.25	133.7911	Al-Br stretch (terminal)
17	502.58	104.1962	Al-Cl stretch (terminal)
18	615.03	177.0592	Al-Cl stretch (terminal)

|

This is where you add your explanation of why there are fewer vibrational peaks than there are vibrations.(Because some of the energy levels are degenerate and so give rise to only one peak in the spectrum.

B3LYP/6-31G level, Isomer 4

Optimisation log file here

summary data

convergence

Jmol

  Item               Value     Threshold  Converged?
 Maximum Force            0.000023     0.000450     YES
 RMS     Force            0.000012     0.000300     YES
 Maximum Displacement     0.000867     0.001800     YES
 RMS     Displacement     0.000316     0.001200     YES
 Predicted change in Energy=-2.548056D-08
 Optimization completed.

optimised BH3 molecule

Al₂Cl₂Br₂ Isomer 4 Symmetry

Optimisation log file here


summary data	low modes
	Low frequencies --- -4.2111 -2.4732 0.0025 0.0030 0.0042 0.9356 Low frequencies --- 17.0899 50.8290 78.6237

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 4


Mode	Frequency	Intensity	Type
1	17.09	0.4359	Al-Cl bend (bridge)
5	103.64	2.7204	Al-Cl bend (bridge
6	120.57	12.8808	Al-Br/Al-Cl bend bend (terminal)
7	122.25	6.0119	Al-Cl bend
9	158.47	5.1949	Al-Cl bend
10	194	2	Al-Cl bend
12	279	26	Al-Br/Al-Cl stretch (bridging)
13	309	2	Al-Cl stretch (bridging)
14	413	149	Al-Cl stretch (bridging)
15	420	409	Al-Cl stretch (bridging)
16	461	36	Al-Cl Al-Br stretch (bridging + terminal)
17	570	34	Al-Cl Al-Br stretch (terminal)
18	582	277	Al-Cl stretch (terminal)

|

B3LYP/6-31G level, Isomer 5

Optimisation log file here

summary data

convergence

Jmol

 Item               Value     Threshold  Converged?
 Maximum Force            0.000019     0.000450     YES
 RMS     Force            0.000009     0.000300     YES
 Maximum Displacement     0.000584     0.001800     YES
 RMS     Displacement     0.000198     0.001200     YES
 Predicted change in Energy=-3.789425D-09
 Optimization completed.

optimised BH3 molecule

Al₂Cl₂Br₂ Isomer 5 Symmetry

Optimisation log file here


summary data	low modes
	Low frequencies --- -4.0872 -2.1697 -0.0043 -0.0042 -0.0029 1.2886 Low frequencies --- 17.7558 48.9700 72.9549

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 5


Mode	Frequency	Intensity	Type
6	117	9	Br-Al-Cl bend (terminal)
7	119	13	Al-Br/Al-Cl bend (terminal)
9	160	6	Al-Cl bend (terminal)
12	280	29	Al-Cl stretch (bridging)
14	414	149	Al-Cl stretch (bridging)
15	421	439	Al-Cl stretch (bridging)
18	579	316	Cl-Al-Br Stretch (terminal)

|

Energy Comparison for the Isomers of Al₂Cl₂Br₂


Isomer Energies	ΔE [kJ/mol]
E(2)-E(1)	(-)182.517696kJ/mol
E(3)-E(1)	(-)381.679848kJ/mol
E(4)-E(1)	(-)379.280304kJ/mol
E(5)-E(1)	(-)380.156328kJ/mol

The lowest energy isomers will be those of highest frequency. In the calculations above the lowest energy isomer is isomer 1.

AlCl2Br Monomer

B3LYP/LANL2ZD level

Optimisation log file here

summary data

convergence

Jmol

  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
 Predicted change in Energy=-7.984435D-08
 Optimization completed.

optimised AlCl2Br molecule

For the dissociation of Al₂Cl₂Br₂ into two monomers of AlCl₂Br: Al₂Cl₂Br₂ → 2AlCl₂Br ΔE=1371.77 kJ/mol, showing that the AlCl₂Br would much rather form dimers in order to relieve the electron deficiency on the Aluminium; it is a Lewis acid and will not be very stable as the monomer and will thus accept electron density into its low-lying p-orbitals.

Frequency Comparison 1


Isomer	Mode	Frequency	Intensity	Type
1	13	247	Not IR active
2	16	493	107
3	17	503	104
4	16	461	36
5	16	459	Not IR active

The modes listed in the table shows the displacement of the Al atoms in the same plane as the bridging Cl atoms. Starting off with Isomer 1. as it is symmetrical this mode will not be IR-active as the prerequisite for a molecule to be IR-active is it to have a change in dipole moment, and in this case the change is cancelled out by an equal and opposite motion. However, comparing the displacement of the Al atoms with that of Isomer 2, exchanging one of the bridging Br atoms for one of the terminal Cl atoms induces an asymmetry that results in an IR-active mode which occurs at a higher frequency, 247 vs. 493 [cm−1].

Knowing that $E = h v$ , this is quite a significant difference ΔV=246 [cm−1] showing that the same motion in isomer 2 is of higher energy, since the Frequency, v, is proportional to the Energy, E (E∝v). This is, however, expected since the Al-Cl bond is stronger than the Al-Br bond.

Interestingly, the difference in frequency between isomer 2 and isomer 3 is not great, ΔV=10 [cm−1] indicating that it does not make that big of a difference if the Br-atoms are placed in geminal (terminal) or bridging position. Comparing isomer 4 and isomer 5, the difference between if the terminal Br-atoms are cis or trans does not produce a significant difference; ΔV=2 [cm−1], (where cis is the higher energy isomer) and so in conclusion the trans vs. cis configuration does not produce as large difference in frequency as compared to geminal terminal or bridging indicating that it is the number of bonds between the atoms that is significant.

Frequency Comparison 2


Isomer	Mode	Frequency	Intensity	Type
1	18	616	332
2	17, 18	574, 615	122, 197
3	16, 18	495, 615	134, 177
4	18	582	277
5	18	579	316

From looking at the modes where the Aluminium atoms are moving up and down in an orthogonal motion to the bridging Br/Cl atoms one can tell that the asymmetry that is induced in isomer 2 and 3 give rise to two modes instead of one, 17 and 18 for the orthogonal displacement. Comparing these modes with that of isomer 1 show a difference in frequency Δv=40 cm-1 and Δv=1 cm-1. Mode 18 in isomer 2 where the Al-Cl bond stretches is significantly closer in energy to that of isomer 1 in comparison to mode 17 where the Al is bonded one terminal and one bridging Br atom. This effect is also shown from comparing isomer 2 with isomer 3 where the Δv=79 cm-1 for the mode where the Al with two geminal (terminal) Br atoms are stretching and Δv=0 for the mode where the Al with two geminal (terminal) Br atoms are stretching. And so the effect of having one terminal and one bridging Br atom only have a significant effect on stretches of bonds of atoms that are directly bonded to the Br atoms. As in Frequency Comparison 1. for isomer 4 and 5 the Δv=3cm-1, and like before the higher energy isomer was the cis-configuration.

MO Analysis of Isomers 5

As Isomer 1 and Isomer 5 were lowest in energy, I chose to do a Molecular Orbital Analysis of Isomer 5.


Molecular Orbital 31	Molecular Orbital 34


Molecular Orbital 41	Molecular Orbital 47

References

↑ IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
↑ "Bond Lengths and Energies." UWaterloo, n.d. Web. 21 Nov 2010. http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html.
↑ Frey, Paul Reheard. College Chemistry, 3rd Edition Prentice-Hall. 1965 p. 134.
↑ Michigan State University. Organic Chemistry [web access:23/10/14 20.00] http://www.cem.msu.edu/~reusch/OrgPage/bndenrgy.htm.
↑ Atomic Structure and Periodicity: RSC (Tutorial Chemistry Texts), 2002, J. Barrett, E W Abel, A G Davies, D. Phillips, J D. Woollins), C. Drayton. ISBN-10: 0854046577.

[ChemicalBond-1] IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.

[BondDistance-2] "Bond Lengths and Energies." UWaterloo, n.d. Web. 21 Nov 2010. http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html.

[BondEnergy-3] Frey, Paul Reheard. College Chemistry, 3rd Edition Prentice-Hall. 1965 p. 134.

[TableDistance-4] Michigan State University. Organic Chemistry [web access:23/10/14 20.00] http://www.cem.msu.edu/~reusch/OrgPage/bndenrgy.htm.

[Periodicity-5] Atomic Structure and Periodicity: RSC (Tutorial Chemistry Texts), 2002, J. Barrett, E W Abel, A G Davies, D. Phillips, J D. Woollins), C. Drayton. ISBN-10: 0854046577.

[1]

[2]

[3]

[4]

[5]

Chemical Bonding

Bonding in MX3 and MH3 Species

Software: Gauss View

BH3 Project Section

BH3 Optimisation Data

B3LYP/3-21G level

B3LYP/6-31G level

BH3 Symmetry

Vibrational spectrum for BH3

Molecular Orbital Diagram for BH3

GaBr3 Project Section

GaBr3 Optimisation Data

B3LYP/LANL2ZD level

GaBr3 Symmetry

Vibrational spectrum for GaBr3

BBr3 Project Section

B3LYP/Gen level

NH3 Project Section

NH3 Optimisation Data

B3LYP/6-31G level

NH3 Symmetry

Vibrational spectrum for NH3

Umbrella modes

NBO Analysis/Charge Distribution

Ammonia-Borane NH3BH3 Project Section

NH3 BH3 Optimisation Data

B3LYP/6-31G level

NH3BH3 Symmetry

Vibrational spectrum for BH3NH3

Al2Cl2Br2 Lab Project Section

The Different Isomers of Al2Cl2Br2

B3LYP/6-31G level, Isomer 1

Al2Cl2Br2 Isomer 1 Symmetry

Vibrational spectrum for Al2Cl2Br2 Isomer 1

B3LYP/6-31G level, Isomer 2

Al2Cl2Br2 Isomer 2 Symmetry

Vibrational spectrum for Al2Cl2Br2 Isomer 2

B3LYP/6-31G level, Isomer 3

Al2Cl2Br2 Isomer 3 Symmetry

Vibrational spectrum for Al2Cl2Br2 Isomer 3

B3LYP/6-31G level, Isomer 4

Al2Cl2Br2 Isomer 4 Symmetry

Vibrational spectrum for Al2Cl2Br2 Isomer 4

B3LYP/6-31G level, Isomer 5

Al2Cl2Br2 Isomer 5 Symmetry

Vibrational spectrum for Al2Cl2Br2 Isomer 5

Energy Comparison for the Isomers of Al2Cl2Br2

AlCl2Br Monomer

B3LYP/LANL2ZD level

Frequency Comparison 1

Frequency Comparison 2

MO Analysis of Isomers 5

References

Bonding in MX₃ and MH₃ Species

BH₃ Project Section

BH₃ Optimisation Data

BH₃ Symmetry

Vibrational spectrum for BH₃

Molecular Orbital Diagram for BH₃

GaBr₃ Project Section

GaBr₃ Optimisation Data

GaBr₃ Symmetry

Vibrational spectrum for GaBr₃

BBr₃ Project Section

NH₃ Project Section

NH₃ Optimisation Data

NH₃ Symmetry

Vibrational spectrum for NH₃

Ammonia-Borane NH₃BH₃ Project Section

NH₃ BH₃ Optimisation Data

NH₃BH₃ Symmetry

Vibrational spectrum for BH₃NH₃

Al₂Cl₂Br₂ Lab Project Section

The Different Isomers of Al₂Cl₂Br₂

Al₂Cl₂Br₂ Isomer 1 Symmetry

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 1

Al₂Cl₂Br₂ Isomer 2 Symmetry

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 2

Al₂Cl₂Br₂ Isomer 3 Symmetry

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 3

Al₂Cl₂Br₂ Isomer 4 Symmetry

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 4

Al₂Cl₂Br₂ Isomer 5 Symmetry

Vibrational spectrum for Al₂Cl₂Br₂ Isomer 5

Energy Comparison for the Isomers of Al₂Cl₂Br₂