Rep:Mod:mhl12comp

Comparison of BH₃, BBr₃ and GaBr₃

BH₃

B3LYP/3-21G level

Optimisation log file here

summary data

convergence

Jmol

         Item               Value     Threshold  Converged?
 Maximum Force            0.000220     0.000450     YES
 RMS     Force            0.000106     0.000300     YES
 Maximum Displacement     0.000709     0.001800     YES
 RMS     Displacement     0.000447     0.001200     YES

optimised BH3 molecule

B3LYP/6-31G(d,p) level

Optimisation log file here

summary data

convergence

Jmol

         Item               Value     Threshold  Converged?
 Maximum Force            0.000203     0.000450     YES
 RMS     Force            0.000098     0.000300     YES
 Maximum Displacement     0.000867     0.001800     YES
 RMS     Displacement     0.000415     0.001200     YES

optimised BH3 molecule

Geometry Data

r(E-X) Å	1.19
θ(X-E-X) degrees(º)	120.0

Frequency Analysis

Frequency file: here


summary data	low modes
	Low frequencies --- -10.1940 -10.1821 -3.1776 -0.0012 0.0579 0.4920 Low frequencies --- 1162.9850 1213.1461 1213.1463

Vibrational spectrum for BH₃


wavenumber	Intensity	IR active?	type
1163	93	yes	bend
1213	14	no	bend
1213	14	very slight	bend
2583	0	no	stretch
2716	126	yes	stretch
2716	126	yes	stretch

Calculated MO and LCAO

MO checkpoint file: file

 LCAO MO (Credit to Dr Tricia Hunt, diagram adapted from Year 2 Lecture 4 Tutorial Problem Model Answers)

The calculated MO agrees with the LCAO approximation.

BBr₃

B3LYP/6-31(d,p)LANL2DZ

Optimisation log file here

summary data

convergence

Jmol

         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

optimised BBr3 molecule

Geometry Data

r(E-X) Å	1.93
θ(X-E-X) degrees(º)	120.0

GaBr₃

B3LYP/LanL2DZ

DOI:10042/84995

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

optimised GaBr3 molecule

Geometry Data

r(E-X) Å	2.35
θ(X-E-X) degrees(º)	120.0

Frequency Analysis

Frequency file: here


summary data	low modes
	Low frequencies --- -0.5293 -0.5288 -0.0024 -0.0010 0.0233 1.1993 Low frequencies --- 76.3744 76.3753 99.6981

Vibrational spectrum for GaBr₃


wavenumber	Intensity	IR active?	type
76	3	no	bend
76	3	no	bend
100	9	very slight	bend
197	0	no	stretch
316	57	yes	stretch
316	57	yes	stretch

Structural Comparison

Geometry Data

	BH₃	BBr₃	GaBr₃
r(E-X) Å	1.19	1.93	2.35
θ(X-E-X) degrees(º)	120.0	120.0	120.0

Discussion:

In GaussView, when it thinks the bond length is too long (than its threshold) or the bonding energy is unfavorable, it will not show the bond. This always happens during the optimization process, when GaussView try to optimize the bond length.

We can see that the bond length increases from B-H (BH₃) to B-Br (BBr₃) This is mostly due to the increase in radii of ligands; the mismatch in orbital size causes weaker interaction and thus a larger bond length. Boron and Gallium both belong to Group 13. Here again, down the group radii of Ga is larger than that of B. Hence the bond length of Ga-Br is larger than that of B-Br. However comparing the increment of B-H to B-Br (0.74Å) and B-Br to Ga-Br(0.42Å), the effect of changing a different nature or substantially larger ligand lead to a larger change in bond distance. Chaging the centre atom will lead to corresponding change according to their ionic radii.

Definition of chemical bond (from [[1]]) : When forces acting between two atoms or groups of atoms lead to the formation of a stable independent molecular entity, a chemical bond is considered to exist between these atoms or groups. The principal characteristic of a bond in a molecule is the existence of a region between the nuclei of constant potential contours that allows the potential energy to improve substantially by atomic contraction at the expense of only a small increase in kinetic energy. Not only directed covalent bonds characteristic of organic compounds, but also bonds such as those existing between sodium cations and chloride anions in a crystal of sodium chloride or the bonds binding aluminium to six molecules of water in its environment, and even weak bonds that link two molecules of O2 into O4, are to be attributed to chemical bonds. ^[1] In simple, chemical bond is a 'link' between two atoms/groups, with attractive forces acting on both atoms/groups.

For covalent bond: Taking silica, a stable and abundant compound on Earth, as a benchmark, Si-O having a bond energy of 452 kJ/mol; so bonding energy above 450 kJ/mol, such as multiple bonding C≡N, N≡N, C=O etc., could be considered as very strong bond; however for single bonding, Si-O is one of the strongest bond. Typical C-C bond has a value of 346 kJ/mol which is around 20% lower in energy than that of Si-O. C-C still could be considered a strong bond. Bonding energies which is 50% less than Si-O (say 200 kJ/mol) are considered medium bond. N-N, N-B etc. have bonding energies of 100+ kJ/mol. Bonding energies which is below 100 kJ/mol (an order of magnitude lower than majority of covalent bonding energy)

For ionic bond: Ionic bonds generally have higher bonding energy, ranging from 700-4000 ^[2]

For dative bond: Dative bond is a slightly special case. It is a covalent bond but with a significant dipole on the chemical bond. The more electronegative atom will carry partial negative charge and the more electropositive atom will carry partial positive charge.

However, usually molecules have the characteristics of both ionic bond and covalent bond in itself. Hence theoretical calculation of bond energy does not always agree with the observed bond energy.

Vibrational Comparison

Refer to BH₃ and GaBr₃

Discussion: Anharmonic oscillator/ Morse curve, a better empirical curve fits the experimental better, but in our frequency analysis, we assumed that the vibration works under harmonic oscillation;this means that if we stretch/compress the spring and release it, it will oscillate around its equilibrium position sinusoidally.

F=-k_s(r-r₀), where k_s is the spring constant, r is the length of extension/compression, r₀ is the equilibrium length.

ω=(k_s/μ)^0.5, where μ=reduced mass

ε_υ=[(υ+1/2)ω]/(2πc) where υ= 0,1,2,3,......

Bond length of B-H is considerably shorter than that of Ga-Br. Generally, increment in bond length reduces the bond strength, or in this case we can treat bond strength as 'spring constant', and hence reduces the vibrational frequency. Of course, the reduced mass of both systems does affect the vibrational frequency as well. The higher the reduced mass, Ga-Br(36.8) compare to B-H(0.9), the lower the frequency of wave number. This is rationalized using Hooke's law without considering any relativistic effect or isotopes effect. It agrees with our calculation; GaBr3 IR spectrum has bands ranging from 70-300, while BH3 IR spectrum ranges from 1000-3000

The frequency of A2" umbrella motion of BH₃ and GaBr₃ 1163 and 100 respectively. The difference in frequencies has been explained above. Umbrella motion of BH₃ is mode #1 with a high intensity (93), while umbrealla motion of GaBr₃ is mode #3 with low intensity (9). This is most probably due to a change in reduced mass and bond strength; leading to reorder of vibration modes. The intensity of the Ir spectrum relates to the amplitude of oscillation. The higher the amplitude the higher larger the intensity. And comparing the vibrating animation of both molecules, in BH₃, Boron and hydrogen did vibrate relative to each other, while in the case of GaBr₃ only Ga is moving. Usually, the stom with relatively lighter mass will vibrate will a larger amplitude than the one that is heavier.

In this lab, all comparison should be run under same basis set. This is to compare two things in a same manner; basis could be thought as a fixed variable, and an experiment should only have one responding variable. Frequency analysis is to make sure the optimisation process does provide a minima. Low frequencies in the calculation represents translational and rotational motion which should be excluded from the vibrational spectrum.

Bonding analysis of NH₃BH₃

BH₃

B3LYP/6-31G(d,p) level optimisation and frequency analysis, refer to here

NH₃

B3LYP/6-31G(d,p) 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

optimised GaBr3 molecule

Geometry Data

Frequency

DOI:10042/90430

Frequency file: here


summary data	low modes
	Low frequencies --- -0.0129 -0.0027 0.0005 7.0724 8.1020 8.1023 Low frequencies --- 1089.3849 1693.9369 1693.9369

Vibrational spectrum for NH₃


wavenumber	Intensity	IR active?	type
1089	145	yes	bend
1694	14	very slight	bend
1694	14	very slight	bend
3461	1	no	stretch
3590	0	no	stretch
3590	0	no	stretch

NH₃ with C3V point group has relatively small number of IR active bands.

Population Analysis

NBO analysis log: here

Nitrogen is a more electronegative atoms and hence has a more negative dipole. And since NH₃ is a neutral molecule, hence the dipole will adds up and give 0.

Bond orbital/ Coefficients/ Hybrids


(Occupancy)   Bond orbital/ Coefficients/ Hybrids
 ---------------------------------------------------------------------------------
     1. (1.99909) BD ( 1) N   1 - H   2  
                ( 68.83%)   0.8297* N   1 s( 24.86%)p 3.02( 75.05%)d 0.00(  0.09%)
                                            0.0001  0.4986  0.0059  0.0000  0.0000
                                            0.0000  0.8155  0.0277 -0.2910  0.0052
                                            0.0000  0.0000 -0.0281 -0.0087  0.0013
                ( 31.17%)   0.5583* H   2 s( 99.91%)p 0.00(  0.09%)
                                            0.9996  0.0000  0.0000 -0.0289  0.0072
     2. (1.99909) BD ( 1) N   1 - H   3  
                ( 68.83%)   0.8297* N   1 s( 24.86%)p 3.02( 75.05%)d 0.00(  0.09%)
                                            0.0001  0.4986  0.0059  0.0000 -0.7062
                                           -0.0239 -0.4077 -0.0138 -0.2910  0.0052
                                            0.0076  0.0243  0.0140  0.0044  0.0013
                ( 31.17%)   0.5583* H   3 s( 99.91%)p 0.00(  0.09%)
                                            0.9996  0.0000  0.0250  0.0145  0.0072
     3. (1.99909) BD ( 1) N   1 - H   4  
                ( 68.83%)   0.8297* N   1 s( 24.86%)p 3.02( 75.05%)d 0.00(  0.09%)
                                            0.0001  0.4986  0.0059  0.0000  0.7062
                                            0.0239 -0.4077 -0.0138 -0.2910  0.0052
                                           -0.0076 -0.0243  0.0140  0.0044  0.0013
                ( 31.17%)   0.5583* H   4 s( 99.91%)p 0.00(  0.09%)
                                            0.9996  0.0000 -0.0250  0.0145  0.0072
     4. (1.99982) CR ( 1) N   1           s(100.00%)
                                            1.0000 -0.0002  0.0000  0.0000  0.0000
                                            0.0000  0.0000  0.0000  0.0000  0.0000
                                            0.0000  0.0000  0.0000  0.0000  0.0000
     5. (1.99721) LP ( 1) N   1           s( 25.38%)p 2.94( 74.52%)d 0.00(  0.10%)
                                            0.0001  0.5036 -0.0120  0.0000  0.0000
                                            0.0000  0.0000  0.0000  0.8618 -0.0505
                                            0.0000  0.0000  0.0000  0.0000 -0.0310
     6. (0.00000) RY*( 1) N   1           s( 99.98%)p 0.00(  0.02%)d 0.00(  0.00%)

BD refers to bonding orbital, CR refers to core orbital and LP refers to lone pair. The first, second and third BD shows that N-H orbital, which 69% contributed by nitrogen atoms. And nitrogen orbital is sp³ hybridized while H orbital is purely s. The core orbital of nitrogen are purely s. The lone pair of nitrogen is sp³ hybridised as well.

NH₃BH₃

B3LYP/6-31G(d,p) level

Optimisation log file here

summary data

convergence

Jmol

         Item               Value     Threshold  Converged?
 Maximum Force            0.000003     0.000015     YES
 RMS     Force            0.000001     0.000010     YES
 Maximum Displacement     0.000022     0.000060     YES
 RMS     Displacement     0.000010     0.000040     YES

optimised GaBr3 molecule

Frequency analysis

Frequency file: here


summary data	low modes
	Low frequencies --- -5.8792 -0.3571 -0.0537 -0.0014 1.0077 1.1094 Low frequencies --- 263.2802 632.9504 638.4510

Vibrational spectrum for NH₃BH₃


wavenumber	Intensity	IR active?	type
262	0	no	bend
633	14	very slight	stretch
638	4	no	bend
638	4	no	bend
1069	41	yes	bend
1069	41	yes	bend
1069	41	yes	bend
1196	109	yes	bend
1204	3	no	bend
1204	3	no	bend
1676	28	yes	bend
1676	28	yes	bend
2472	67	yes	stretch
2532	231	yes	stretch
2532	231	yes	stretch
3464	3	no	stretch
3581	28	yes	stretch
3581	28	yes	stretch

Bond Energy

E(NH₃)= -56.55776873 a.u.

E(BH₃)= -26.61532364 a.u.

E(NH₃BH₃)= -83.22468908 a.u.

ΔE=E(NH₃BH₃) - [E(NH₃)+E(BH₃)]

 = -83.22468908 a.u. - [-56.55776873 a.u. -26.61532364 a.u.]
 
 = -0.05159671 a.u.
 
 = -135.47 kJ/mol (2 d.p.)

Discussion: As this N->B a dative covalent bond, we are comparing N-B bond with normal type of covalent bond. C-C bond which is isoelectronic to N-B bond; typical C-C bond has a bond energy of 346kJ/mol. Hence N-B bond is slightly weaker bond relative to C-C bond. Considering that bond energy of N-B is still of the same order of magnitude with C-C bond, and the fact that the bond energy is way above interaction of hydrogen bonding (typical value 8-30 kJ/mol, except F-H-F), it can be said that N-B bond is a medium(strength) bonding.

2nd Week Project - Lewis Acids and Bases

Optimization of Al₂Cl₂Br₄

The optimization process was computed using 'GEN' basis set and keywords pseudo=cards gfinput. This allow us to specify basis set for each atoms individually. The following instructions were added into the gjf files:


Al 0
6-31G(d,p)
****
Cl 0
6-31G(d,p)
****
Br 0
LanL2DZ
****

Br 0
LanL2DZ

Compound

Isomer 1

Isomer 2

Isomer 3

Isomer 4

Covergence Data

         Item               Value     Threshold  Converged?
 Maximum Force            0.000005     0.000015     YES
 RMS     Force            0.000001     0.000010     YES
 Maximum Displacement     0.000008     0.000060     YES
 RMS     Displacement     0.000003     0.000040     YES

         Item               Value     Threshold  Converged?
 Maximum Force            0.000002     0.000015     YES
 RMS     Force            0.000001     0.000010     YES
 Maximum Displacement     0.000017     0.000060     YES
 RMS     Displacement     0.000007     0.000040     YES

         Item               Value     Threshold  Converged?
 Maximum Force            0.000001     0.000015     YES
 RMS     Force            0.000000     0.000010     YES
 Maximum Displacement     0.000018     0.000060     YES
 RMS     Displacement     0.000007     0.000040     YES

         Item               Value     Threshold  Converged?
 Maximum Force            0.000001     0.000015     YES
 RMS     Force            0.000000     0.000010     YES
 Maximum Displacement     0.000016     0.000060     YES
 RMS     Displacement     0.000005     0.000040     YES

File Type

.log

Calculation Type

FOPT

Calculation Method

RB3LYP

Basis Set

Gen

Charge

0

Spin

Singlet

E(RB3LYP) / a.u.

-1458.35116016

-1458.34598708

-1458.34122428

-1458.34120346

RMS Gradient Norm / a.u.

0.00000222

0.00000255

0.00000034

Imaginary Freq

Dipole Moment / Debye

0.0002

0.1240

0.0002

0.1707

Point Group

C1

Job cpu time

0 days 0 hours 5 minutes 38.8 seconds

0 days 0 hours 17 minutes 56.6 seconds

0 days 0 hours 10 minutes 9.1 seconds

0 days 0 hours 12 minutes 48.1 seconds

D-Space Link

All calculations have been confirmed with the convergence of the data. The optimization will then be further confirmed with frequency analysis (±15cm^-1 for the low frequencies mode as a benchmark to check the optimization process)

	Computational bond length / Å
Terminal Br-Al	2.28
Terminal Cl-Al	2.09
Bridging Br-Al	2.49
Bridging Cl-Al	2.30

Bridging atom and aluminium has a longer bond length that of terminal Al-halides bond indicates that it is not a conventional 2c-2e bond.

Discussion

	Energy reported / a.u.	Relative Energy / a.u.	Relative Energy / KJ/mol
Isomer 1	-1458.35116016	0	0
Isomer 2	-1458.34598708	0.00517308	13.58
Isomer 3	-1458.34122428	0.00993588	26.14
Isomer 4	-1458.34120346	0.00995670	26.14

Isomer has the lowest energy indicates that it is the most stable isomer. As we exchange one bridging Cl with one terminal Br, the energy increases by 13.58 kJ/mol, and increases another 13.06 kJ/mol to 26.14 kJ/mol as we remove one more bridging Cl. And the cis/trans configuration of Cl (isomer 3 and 4) does not have significant changes in energy. From the evidence above, it is likely that Cl is more favourable as bridging atom than Br. This is probably due to Cl, with higher electronegativities, are more compatible with the high lewis acidity Al atom.

Dissociation energy

E(Al₂Cl₂Br₄)= -1458.35116016 a.u.

E(AlClBr₂)= -26.61532364 a.u. *Refer to DOI:10042/107530

ΔE=E(Al₂Cl₂Br₄) - 2*E(AlClBr₂)

 = -1458.35116016 a.u. - 2*[ -729.15823878 a.u.]
 
 = -0.0346826 a.u.
 
 = -91.06 kJ/mol (2 d.p.)

Frequency Analysis

Compound

Isomer 1

Isomer 2

Isomer 3

Isomer 4

Calculation Method

RB3LYP

Basis Set

Gen

Charge

0

Spin

Singlet

E(RB3LYP) / a.u.

-1458.35116016

-1458.34598708

-1458.34122763

-1458.34120346

RMS Gradient Norm / a.u.

0.0000441

0.00000255

0.00000753

0.00000064

Imaginary Freq

0

Dipole Moment / Debye

0.0000

0.1240

0.0000

0.1707

Point Group

D2H

C1

C2H

C2V

Job cpu time

0 days 0 hours 0 minutes 50.0 seconds

0 days 0 hours 2 minutes 22.4 seconds

0 days 0 hours 1 minutes 0.9 seconds

0 days 0 hours 1 minutes 1.7 seconds.

Low Modes

Low frequencies --- -3.5251 -2.2048 -0.0030 -0.0022 -0.0019  1.9779
Low frequencies --- 15.0148 38.6160 59.6441

Low frequencies --- -2.6621 -0.0021 -0.0018  0.0018  2.1611  3.3401
Low frequencies --- 14.5344 44.1267 64.0506

Low frequencies --- -5.0200 -3.3842 -3.0570  0.0035  0.0039  0.0041
Low frequencies --- 12.4814 47.7011 67.3961

Low frequencies --- -4.8432 -3.3720 -3.0141 -0.0025 -0.0016  0.0013
Low frequencies --- 12.2710 49.9139 71.1649

D-Space Link

IR Spectra

Wavenumber	Intensity	IR active?	Mode
15	0	No	Bend (scissors)
39	0	No	Bend (twisting)
60	0	No	Bend (scissors)
83	0	No	Bend (Twisting)
97	8	Yes	Bend
101	7	Yes	Bend
105	0	No	Bend
145	0	No	Bend
158	5	Yes	Bend
158	0	No	Bend
243	6	Yes	Symmetric Bridging Cl Al stretch (Cl)
261	0	No	Asymmetric Cl Al stretch
291	0	No	Bend
400	463	Yes	Symmetric Bridging Cl Al stretch (Al)
408	139	Yes	Bend
445	0	No	Ring breathing
491	0	No	Antisymmetric Terminal Br Al stretch
501	289	Yes	Antisymmetric Terminal Br Al stretch

Wavenumber	Intensity	IR active?	Mode
15	0	No	Bend
44	0	No	Bend
64	0	No	Bend
82	1	No	Bend
88	0	No	Bend
95	4	Slightly	Bend
104	6	Yes	Bend
135	3	Yes	Bend
141	5	Yes	Bend
163	0	No	Bend
200	17	Yes	Asymmetric Bridging Br Al stretch
238	7	Slightly	Symmetric Terminal Br Al stretch
265	13	Yes	Asymmetric Bridging Cl Al stretch
374	149	Yes	Symmetric bridging Br stretch
395	374	Yes	Terminal Br Al stretch
438	32	Yes	Bridging Br bend
496	132	Yes	Antisymmetric Terminal Br Al stretch
575	170	Yes	Terminal Al Cl stretch

Wavenumber	Intensity	IR active?	Mode
12	0	No	Bend
48	0	No	Bend
67	0	No	Bend
76	0	No	Bend
98	4	Yes	Bend
98	0	No	Bend
105	5	Yes	Bend
123	7	Yes	Bend
125	0	No	Bend
151	0	No	Bend
193	0	No	Bend
216	58	Yes	Bend
218	0	No	Symmetric ring breathing
334	147	Yes	Bridging Br Al stretch
398	374	Yes	Asymmetric Terminal Br Al stretch
426	0	No	Terminal Br Al stretch
571	0	No	Symmetric Terminal Cl Al stretch
576	314	Yes	Asymmetric Terminal Cl Al stretch

Wavenumber	Intensity	IR active?	Mode
12	0	No	Bend
50	0	No	Bend
71	0	No	Bend
73	0	No	Bend
90	0	No	Bend
99	3	NO	Bend
111	7	Yes	Bend
123	5	Yes	Bend
124	0	No	Bend
152	0	No	Bend
193	0	No	Bend
216	57	Yes	Bend
219	1	No	Symmetric Bridging Br Al stretch
334	147	Yes	Symmetric Bridging Br Al stretch
397	348	Yes	Terminal Br/Cl Al stretch
427	29	Yes	Terminal Br/Cl Al stretch
569	31	Yes	Terminal Br/Cl Al stretch
578	282	Yes	Terminal Br/Cl Al stretch

Discussion

A molecule must have stretch or bent and created a change in dipole in order to be IR active. Hence, the higher the symmetry of molecules, the less IR active band exist due to many symmetric stretches and bent will not create a change in dipole.

The point groups of the four isomers above are highlighted in the table. Isomer 2 belongs to C1 group, the group with only E symmetry elements, thus it has the most IR bands. The other 3 isomers have higher symmetry, hence they have less IR bands.

Bridging halide- Al stretch gives a lower wavenumber, it is most probably due to the reasoning that the bond length has become substantially longer than that of terminal halide-Al. The reasoning could be found on the discussion of vibrational frequency of Ga-Br and B-H. And chlorine vibrate more strongly than bromine, most probably due to their masses.

In the IR spectrum from above, for example in spectrum in isomer 1, for the same symmetrical stretching of Cl- Al, it can be due to vibrational movement of Cl or Al or both. They have different frequencies and intensities. The reordering of vibrational modes make it hard to analyse and we have to examine all vibrational movement one by one. Bridging halides vibrate in a smaller amplitude than terminal halide; this is most probably due to the 3c-4e bonding.

The cis trans configuration does not affect the IR spectrum significantly. They both have similar stretches at similar frequencies with similar intensities. The reorder of modes does not manifest in this case is due to the fact that both the molecules have the same element in it. And the configuration of the molecules is very similar in a way that the bridging molecules remain to be Br, only changing the position of terminal halides.

MO Analysis

5 MOs of Isomer 1 of Al₂Cl₂Br₄ are investigated for this project. All files for MO analysis can be obtained from DOI:10042/107495

Strong bonding -> Medium bonding -> Weak bonding -> Medium antibonding -> Strong antibonding

NBO analysis

       (Occupancy)   Bond orbital/ Coefficients/ Hybrids
 ---------------------------------------------------------------------------------
     1. (1.96691) BD ( 1)Al   1 -Cl   3  
                ( 12.14%)   0.3484*Al   1 s( 20.28%)p 3.77( 76.46%)d 0.16(  3.26%)
                                            0.0000 -0.0011  0.4501  0.0142  0.0003
                                           -0.5362 -0.0191  0.0000  0.0000  0.0000
                                            0.0002  0.6887  0.0496  0.0000 -0.1524
                                            0.0000  0.0816  0.0519
                ( 87.86%)   0.9374*Cl   3 s( 23.62%)p 3.23( 76.20%)d 0.01(  0.18%)
                                            0.0000 -0.0002  0.4859  0.0120  0.0000
                                            0.7062  0.0012  0.0000  0.0000  0.0000
                                            0.0000 -0.5131  0.0036  0.0000 -0.0356
                                            0.0000  0.0121  0.0191
     2. (1.96691) BD ( 1)Al   1 -Cl   4  
                ( 12.14%)   0.3484*Al   1 s( 20.28%)p 3.77( 76.46%)d 0.16(  3.26%)
                                            0.0000 -0.0011  0.4501  0.0142  0.0003
                                           -0.5362 -0.0191  0.0000  0.0000  0.0000
                                           -0.0002 -0.6887 -0.0496  0.0000  0.1524
                                            0.0000  0.0816  0.0519
                ( 87.86%)   0.9374*Cl   4 s( 23.62%)p 3.23( 76.20%)d 0.01(  0.18%)
                                            0.0000 -0.0002  0.4859  0.0120  0.0000
                                            0.7062  0.0012  0.0000  0.0000  0.0000
                                            0.0000  0.5131 -0.0036  0.0000  0.0356
                                            0.0000  0.0121  0.0191
     3. (1.96807) BD ( 1)Al   1 -Br   7  
                ( 21.17%)   0.4601*Al   1 s( 29.66%)p 2.28( 67.62%)d 0.09(  2.73%)
                                            0.0000 -0.0001  0.5445 -0.0056  0.0001
                                            0.4361  0.0324  0.0000 -0.6941 -0.0568
                                            0.0000  0.0000  0.0000 -0.1228  0.0000
                                            0.0000 -0.0847 -0.0708
                ( 78.83%)   0.8878*Br   7 s( 22.57%)p 3.43( 77.43%)
                                            0.4751 -0.0033 -0.4319 -0.0109  0.7662
                                            0.0230  0.0000  0.0000
     4. (1.96807) BD ( 1)Al   1 -Br   8  
                ( 21.17%)   0.4601*Al   1 s( 29.66%)p 2.28( 67.62%)d 0.09(  2.73%)
                                            0.0000 -0.0001  0.5445 -0.0056  0.0001
                                            0.4361  0.0324  0.0000  0.6941  0.0568
                                            0.0000  0.0000  0.0000  0.1228  0.0000
                                            0.0000 -0.0847 -0.0708
                ( 78.83%)   0.8878*Br   8 s( 22.57%)p 3.43( 77.43%)
                                            0.4751 -0.0033 -0.4319 -0.0109 -0.7662
                                           -0.0230  0.0000  0.0000
     5. (1.96691) BD ( 1)Al   2 -Cl   3  
                ( 12.14%)   0.3484*Al   2 s( 20.28%)p 3.77( 76.46%)d 0.16(  3.26%)
                                            0.0000  0.0011 -0.4501 -0.0142  0.0003
                                           -0.5362 -0.0191  0.0000  0.0000  0.0000
                                           -0.0002 -0.6887 -0.0496  0.0000 -0.1524
                                            0.0000 -0.0816 -0.0519
                ( 87.86%)   0.9374*Cl   3 s( 23.62%)p 3.23( 76.20%)d 0.01(  0.18%)
                                            0.0000  0.0002 -0.4859 -0.0120  0.0000
                                            0.7062  0.0012  0.0000  0.0000  0.0000
                                            0.0000  0.5131 -0.0036  0.0000 -0.0356
                                            0.0000 -0.0121 -0.0191
     6. (1.96691) BD ( 1)Al   2 -Cl   4  
                ( 12.14%)   0.3484*Al   2 s( 20.28%)p 3.77( 76.46%)d 0.16(  3.26%)
                                            0.0000  0.0011 -0.4501 -0.0142  0.0003
                                           -0.5362 -0.0191  0.0000  0.0000  0.0000
                                            0.0002  0.6887  0.0496  0.0000  0.1524
                                            0.0000 -0.0816 -0.0519
                ( 87.86%)   0.9374*Cl   4 s( 23.62%)p 3.23( 76.20%)d 0.01(  0.18%)
                                            0.0000  0.0002 -0.4859 -0.0120  0.0000
                                            0.7062  0.0012  0.0000  0.0000  0.0000
                                            0.0000 -0.5131  0.0036  0.0000  0.0356
                                            0.0000 -0.0121 -0.0191
     7. (1.96807) BD ( 1)Al   2 -Br   5  
                ( 21.17%)   0.4601*Al   2 s( 29.66%)p 2.28( 67.62%)d 0.09(  2.73%)
                                            0.0000 -0.0001  0.5445 -0.0056 -0.0001
                                           -0.4361 -0.0324  0.0000  0.6941  0.0568
                                            0.0000  0.0000  0.0000 -0.1228  0.0000
                                            0.0000 -0.0847 -0.0708
                ( 78.83%)   0.8878*Br   5 s( 22.57%)p 3.43( 77.43%)
                                            0.4751 -0.0033  0.4319  0.0109 -0.7662
                                           -0.0230  0.0000  0.0000
     8. (1.96807) BD ( 1)Al   2 -Br   6  
                ( 21.17%)   0.4601*Al   2 s( 29.66%)p 2.28( 67.62%)d 0.09(  2.73%)
                                            0.0000 -0.0001  0.5445 -0.0056 -0.0001
                                           -0.4361 -0.0324  0.0000 -0.6941 -0.0568
                                            0.0000  0.0000  0.0000  0.1228  0.0000
                                            0.0000 -0.0847 -0.0708
                ( 78.83%)   0.8878*Br   6 s( 22.57%)p 3.43( 77.43%)
                                            0.4751 -0.0033  0.4319  0.0109  0.7662
                                            0.0230  0.0000  0.0000

The bonding orbitals of Al, Cl and Br are sp³ hybridized.

References

1.^[1]http://goldbook.iupac.org/CT07009.html 2.^[2]http://science.jrank.org/pages/984/Bond-Energy.html

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[1]

[2]

Comparison of BH3, BBr3 and GaBr3

BH3

B3LYP/3-21G level

B3LYP/6-31G(d,p) level

Geometry Data

Frequency Analysis

Vibrational spectrum for BH3

Calculated MO and LCAO

BBr3

B3LYP/6-31(d,p)LANL2DZ

Geometry Data

GaBr3

B3LYP/LanL2DZ

Geometry Data

Frequency Analysis

Vibrational spectrum for GaBr3

Structural Comparison

Vibrational Comparison

Bonding analysis of NH3BH3

BH3

NH3

B3LYP/6-31G(d,p) level

Geometry Data

Frequency

Vibrational spectrum for NH3

Population Analysis

Bond orbital/ Coefficients/ Hybrids

NH3BH3

B3LYP/6-31G(d,p) level

Frequency analysis

Vibrational spectrum for NH3BH3

Bond Energy

2nd Week Project - Lewis Acids and Bases

Optimization of Al2Cl2Br4

Discussion

Dissociation energy

Frequency Analysis

Discussion

MO Analysis

NBO analysis

References

Comparison of BH₃, BBr₃ and GaBr₃

BH₃

Vibrational spectrum for BH₃

BBr₃

GaBr₃

Vibrational spectrum for GaBr₃

Bonding analysis of NH₃BH₃

BH₃

NH₃

Vibrational spectrum for NH₃

NH₃BH₃

Vibrational spectrum for NH₃BH₃

Optimization of Al₂Cl₂Br₄