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Week 1 Inorganic computational

BH3

BH3 optimisation

BH3 optimisation [BH3 321G optimisation]
File Name SW_BH3_OPT
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set 3-21G
Change 0
Spin Singlet
E(RB3LYP) -26.46226429 a.u.
RMS Gradient Norm 0.00008851 a.u.
Imaginary Freq
Dipole Moment 0.0003 Debye
Point Group CS
Job cpu time: 0 days 0 hours 0 minutes 20.0 seconds.
 BH3 Optimisation 
         Item               Value     Threshold  Converged?
 Maximum Force            0.000220     0.000450     YES
 RMS     Force            0.000106     0.000300     YES
 Maximum Displacement     0.000940     0.001800     YES
 RMS     Displacement     0.000447     0.001200     YES
 Predicted change in Energy=-1.672479D-07
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1948         -DE/DX =   -0.0002              !
 ! R2    R(1,3)                  1.1947         -DE/DX =   -0.0002              !
 ! R3    R(1,4)                  1.1944         -DE/DX =   -0.0001              !
 ! A1    A(2,1,3)              120.0157         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              119.986          -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              119.9983         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad
 
BH3 optimisation 631G [BH3 631G optimisation]
File Name SW_bh3_opt_631G
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -26.61532358 a.u.
RMS Gradient Norm 0.00008206 a.u.
Imaginary Freq
Dipole Moment 0.0003 Debye
Point Group CS
Job cpu time: 0 days 0 hours 0 minutes 14.0 seconds.
Optimised Bond Length 1.19, 1.19, 1.19 Å
Optimised Bond Angle 120.0, 120.0, 120.0
 BH3 Optimisation 631G
 Item               Value     Threshold  Converged?
 Maximum Force            0.000204     0.000450     YES
 RMS     Force            0.000099     0.000300     YES
 Maximum Displacement     0.000875     0.001800     YES
 RMS     Displacement     0.000418     0.001200     YES
 Predicted change in Energy=-1.452086D-07
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1928         -DE/DX =   -0.0002              !
 ! R2    R(1,3)                  1.1926         -DE/DX =   -0.0002              !
 ! R3    R(1,4)                  1.1924         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0146         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              119.9866         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              119.9988         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad
 

BH3 optimisation 631G 2nd time

BH3 optimisation 2nd time [BH3 321G optimisation 2nd]
File Name BH3_OPT_3
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -26.61532364 a.u.
RMS Gradient Norm 0.00000000 a.u.
Imaginary Freq
Dipole Moment 0.0000 Debye
Point Group D3H
Job cpu time: 0 days 0 hours 0 minutes 9.0 seconds.
Optimised Bond Length 1.19, 1.19, 1.19 Å
Literature Bond Lengthlit 2 1.2325 Å
Optimised Bond Angle 120.0, 120.0, 120.0
 BH3 Optimisation 2nd time
         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000002     YES
 RMS     Force            0.000000     0.000001     YES
 Maximum Displacement     0.000000     0.000006     YES
 RMS     Displacement     0.000000     0.000004     YES
 Predicted change in Energy=-1.214719D-18
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1923         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.1923         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.1923         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad
 

BH3 Frequency

BH3 Frequency [BH3 Frequency]
File Name SW_BH3_FREQ
File Type .log
Calculation Type FREQ
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -26.61532358 a.u.
RMS Gradient Norm 0.00008199 a.u.
Imaginary Freq 0
Dipole Moment 0.0003 Debye
Point Group CS
Job cpu time: 0 days 0 hours 0 minutes 11.0 seconds.
 BH3 Frequency
 Low frequencies --- 0.0006    0.0007    0.0007   33.8245   41.5797   43.6874
 Low frequencies --- 1163.5016 1213.4680 1213.5880

comment since the frequency is too high. Therefore point group constraint is added to run a 2nd time.

BH3 Frequency 2nd

BH3 Frequency 2nd [BH3 Frequency 2nd]
File Name BH3_FREQ_3
File Type .log
Calculation Type FREQ
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -26.61532364 a.u.
RMS Gradient Norm 0.00000001 a.u.
Imaginary Freq 0
Dipole Moment 0.0000 Debye
Point Group D3H
Job cpu time: 0 days 0 hours 0 minutes 6.0 seconds.
 BH3 Frequency
 Low frequencies ---   -9.3741   -9.3588   -0.0753    0.0007    0.5350    2.4499
 Low frequencies --- 1162.9902 1213.1495 1213.1497

BH3 Vibration

BH3 Vibration
No. Form of the Vibration Frequency Vibration Symmetry of D3H Point group
1
Symmetric stretching. all H atoms in and out of the plane, B atom is going the opposite direction slowly
1163 93 A2"
2
Assymmetric stretching. H atoms are rocking and scissoring at the same time. B atom moves slightly
1213 14 E'
3
two H atoms are Scissoring, B atom and the other H atom are moving slightly
1213 14 E'
4
Symmetrical stretching. all H atoms moves towards and opposite to the centre, B atom remains stationary
2583 0 A1'
5
Assymmetric stretching of two H atoms. The other two atoms vibrate a bit at their points
2716 126 E'
6
It is symmetrical stretching of two of the H atoms while the other H is doing assymmetrical to them. The B atom changes a bit at its position.
2716 126 E'

In your wiki also explain why are there less than six peaks in the spectrum, when there are obviously six vibrations.

There are indeed six vibrational modes shown in the table. However, the No.2 and No.3 both have frequency at 1213 cm-1 and No. 5 and No. 6 both have the same frequency at 2716 cm-1. So they overlap to each other and only appear two peaks. On the other hand, the vibration of No. 4 is zero, as it is symmetrical stretching and no change in dipole. So it is IR inactive. Therefore there are only 3 peaks appear in the spectrum.

Molecular Orbital of BH3

[Molecular Orbital of BH3 D space]

Answer the following questions:

Are there any significant differences between the real and LCAO MOs?

What does this say about the accuracy and usefulness of qualitative MO theory?

GaBr3

GaBr3 optimisation

GaBr3 optimisation [GaBr3 LANL2DZ optimisation] [GaBr3 optimisation D space]
File Name SW_GABR3_OPT
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set LANL2DZ
Change 0
Spin Singlet
E(RB3LYP) -41.70082783 a.u.
RMS Gradient Norm 0.00000016 a.u.
Imaginary Freq
Dipole Moment 0.0000 Debye
Point Group D3H
Job cpu time: 0 days 0 hours 0 minutes 6.0 seconds.
Optimised Bond Length 2.35, 2.35, 2.35 Å
Literature Bond Lengthlit 2 2.3525 Å
Optimised Bond Angle 120.0, 120.0, 120.0
 GaBr3 optimisation
 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=-1.282691D-12
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  2.3502         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  2.3502         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  2.3502         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0            -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0            -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0            -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

GaBr3 Frequency

GaBr3 Frequency 2nd [GaBr3 Frequency] [GaBr3 Frequency D space]
File Name SW_GABR3_FREQ
File Type .log
Calculation Type FREQ
Calculation Method RB3LYP
Basis Set LANL2DZ
Change 0
Spin Singlet
E(RB3LYP) -41.70082783 a.u.
RMS Gradient Norm 0.00000011 a.u.
Imaginary Freq 0
Dipole Moment 0.0000 Debye
Point Group D3H
Job cpu time: 0 days 0 hours 0 minutes 6.0 seconds.
 GaBr<sub>3</sub> Frequency
 Low frequencies ---   -0.5252   -0.5247   -0.0024   -0.0010    0.0235    1.2010
 Low frequencies ---   76.3744   76.3753   99.6982

GaBr3_IRspectrum

BBr3

BBr3 optimisation

BBr3 optimisation [BBr3 optimisation] [BBr3 optimisation D space]
File Name SW_BBr3_OPT_GEN
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set Gen
Change 0
Spin Singlet
E(RB3LYP) -64.43644666 a.u.
RMS Gradient Norm 0.00001415 a.u.
Imaginary Freq
Dipole Moment 0.0003 Debye
Point Group CS
Job cpu time: 0 days 0 hours 0 minutes 15.0 seconds.
Optimised Bond Length 1.93, 1.93, 1.93 Å
Literature Bond Lengthlit 2 1.893 Å
Optimised Bond Angle 120.0, 120.0, 120.0
Reference*** 2.35018
 BBr3 optimisation
         Item               Value     Threshold  Converged?
 Maximum Force            0.000026     0.000450     YES
 RMS     Force            0.000012     0.000300     YES
 Maximum Displacement     0.000131     0.001800     YES
 RMS     Displacement     0.000065     0.001200     YES
 Predicted change in Energy=-3.258105D-09
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.934          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.934          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.9339         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              119.9975         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              120.0005         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.002          -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

Comparisons

Bond lengths Comparisons
Compounds Optimised Bond Length Mean Bond Length
BH3 1.19, 1.19, 1.19 1.19 Å
GaBr3 2.35, 2.35, 2.35 2.35 Å
BBr3 1.93, 1.93, 1.93 1.93 Å

Comments

What difference does changing the ligand have?

How are H and Br similar, how are they different?

What difference does changing the central element make?

How are B and Ga similar, how are they different?''

Change of overlap, change of atom size, change of polarity, change of the electronegativity

Comparing the bond length of BH3 and BBr3, BBr bond is 0.74 Å longer than BH bond. The replacement of the H to Br group leads a poorer overlap between the ligand and boron, because the H has the s orbital overlap while the Br has the p orbital overlap. More electron density in Br increases the size of the atom due to stronger electrostatic repulsion as well as its electronegativity. The electronegativity of H, B and Br are 2.300, 2.051 and 2.685 lit 1 respectively. Therefore the polarity of the molecules is bigger in BBr3. Overall it gives a better interaction in BH3 than BBr3, hence a shorter bond appears in BH3.

The bond length of GaBr3 is 0.42 longer than BBr3. Both of Ga and B are in group 13, so their frontier orbitals are both p orbital. However Ga is a transition metal and B is electron deficient. So the 4p orbital in Ga is more deffused. As the group is going down, the size of the central element goes up as a consequence of the poorer overlap between the central atom and ligands. Ga is also more electropositive (1.756 lit 1) than B. So the bigger polarity leads to a weaker overlap and gives a longer bond.

Short Questions*****

answer the following in your wiki (your reply should be 2-3 paragraphs in length)

In some structures gaussview does not draw in the bonds where we expect, does this mean there is no bond? Why?

What is a bond?

A bond ....

Therefore in some structures, it doesn't mean there is no bond although Gaussview doesn't draw it out. The first few structures don't have any bonds. Gaussview draws bonds based on a

distance critera, so the fact that gaussview hasn't drawn bonds doesn't mean they are
not there! Just that the distance exceeds some pre-defined value.


vibrational frequencies of BH3 and GaBr3

vibrational frequencies of BH3 and GaBr3
No. Frequency of BH3 Frequency of BH3
1 1163 76
2 1213 76
3 1213 100
4 2583 197
5 2716 316
6 2716 316

What does the large difference in the value of the frequencies for BH3 compared to GaBr3 indicate?

Has there been a reordering of modes?

How are these spectra similar?

For both spectra two modes lie fairly closely together, the A2 and E' modes and then the other two modes also lie fairly close together, the A1' and E' modes, but higher in energy. Why is this?

answer ALL the following in your wiki Why must you use the same method and basis set for both the optimisation and frequency analysis calculations?

What is the purpose of carrying out a frequency analysis?

What do the "Low frequencies" represent?

NH3

NH3 optimisation

NH3 optimisation [NH3 optimisation] [NH3 optimisation D space]
File Name SW_BBr3_OPT_GEN
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -56.55776863 a.u.
RMS Gradient Norm 0.00000289 a.u.
Imaginary Freq
Dipole Moment 1.8464 Debye
Point Group C3V
Job cpu time: 0 days 0 hours 0 minutes 10.0 seconds.
Optimised Bond Length 1.02, 1.02, 1.02 Å
Literature Bond Length*** 2.35018 Å
Optimised Bond Angle 106, 106, 106
Literature Bond Angle*** 2.35018
Reference*** 2.35018
 NH3 optimisation
         Item               Value     Threshold  Converged?
 Maximum Force            0.000005     0.000450     YES
 RMS     Force            0.000003     0.000300     YES
 Maximum Displacement     0.000010     0.001800     YES
 RMS     Displacement     0.000007     0.001200     YES
 Predicted change in Energy=-7.830455D-11
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.018          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.018          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.018          -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              105.7463         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              105.7463         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              105.7463         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)           -111.867          -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

NH3 Frequency

NH3 Frequency [NH3 Frequency] [NH3 Frequency D space]
File Name SW_NH3_freq2
File Type .log
Calculation Type FREQ
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -56.55776873 a.u.
RMS Gradient Norm 0.00000028 a.u.
Imaginary Freq 0
Dipole Moment 1.8465 Debye
Point Group C3V
Job cpu time: 0 days 0 hours 0 minutes 4.0 seconds.
 NH3 Frequency
 Low frequencies ---   -6.1415   -4.4910   -4.4904    0.0014    0.0035    0.0150
 Low frequencies --- 1089.3562 1693.9270 1693.9271

NH3 MO

NH3 MO [NH3 MO] NH3 MO D space]
File Name SW_NH3_MO
File Type .chk
Calculation Type SP
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -56.55776863 a.u.
RMS Gradient Norm 0.00000000 a.u.
Imaginary Freq 0
Dipole Moment 1.8464 Debye
Point Group C3V
Job cpu time: 0 days 0 hours 0 minutes 6.0 seconds.

NH3 NBO Analysis

NH3 NBO [NH3 MO] [NH3 Frequency D space]
NH3 NBO Analysis Comment
charge distributionColour range -1.000 to 1.000
NBO charges for the nitrogen: -1.125 and hydrogen atom: 0.375

NH3BH3

NH3BH3 Optimisation

NH3BH3 Optimisation [NH3BH3 Optimisation ] [NH3BH3 Optimisation D space]
File Name SW_NH3BH3_OPT
File Type .log
Calculation Type FOPT
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -83.22468910 a.u.
RMS Gradient Norm 0.00000031 a.u.
Imaginary Freq 0
Dipole Moment 5.5646 Debye
Point Group C1
Job cpu time: 0 days 0 hours 0 minutes 25.0 seconds.
 NH<sub>3</sub>BH<sub>3</sub> Optimisation
         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000002     YES
 RMS     Force            0.000000     0.000001     YES
 Maximum Displacement     0.000005     0.000006     YES
 RMS     Displacement     0.000002     0.000004     YES
 Predicted change in Energy=-3.646599D-12
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,7)                  1.0185         -DE/DX =    0.0                 !
 ! R2    R(2,7)                  1.0185         -DE/DX =    0.0                 !
 ! R3    R(3,7)                  1.0185         -DE/DX =    0.0                 !
 ! R4    R(4,8)                  1.2098         -DE/DX =    0.0                 !
 ! R5    R(5,8)                  1.2098         -DE/DX =    0.0                 !
 ! R6    R(6,8)                  1.2098         -DE/DX =    0.0                 !
 ! R7    R(7,8)                  1.6677         -DE/DX =    0.0                 !
 ! A1    A(1,7,2)              107.876          -DE/DX =    0.0                 !
 ! A2    A(1,7,3)              107.876          -DE/DX =    0.0                 !
 ! A3    A(1,7,8)              111.023          -DE/DX =    0.0                 !
 ! A4    A(2,7,3)              107.876          -DE/DX =    0.0                 !
 ! A5    A(2,7,8)              111.0227         -DE/DX =    0.0                 !
 ! A6    A(3,7,8)              111.0228         -DE/DX =    0.0                 !
 ! A7    A(4,8,5)              113.8738         -DE/DX =    0.0                 !
 ! A8    A(4,8,6)              113.8739         -DE/DX =    0.0                 !
 ! A9    A(4,8,7)              104.5973         -DE/DX =    0.0                 !
 ! A10   A(5,8,6)              113.8739         -DE/DX =    0.0                 !
 ! A11   A(5,8,7)              104.5975         -DE/DX =    0.0                 !
 ! A12   A(6,8,7)              104.5974         -DE/DX =    0.0                 !
 ! D1    D(1,7,8,4)           -179.9991         -DE/DX =    0.0                 !
 ! D2    D(1,7,8,5)            -59.9992         -DE/DX =    0.0                 !
 ! D3    D(1,7,8,6)             60.0009         -DE/DX =    0.0                 !
 ! D4    D(2,7,8,4)            -59.9991         -DE/DX =    0.0                 !
 ! D5    D(2,7,8,5)             60.0008         -DE/DX =    0.0                 !
 ! D6    D(2,7,8,6)           -179.9991         -DE/DX =    0.0                 !
 ! D7    D(3,7,8,4)             60.0008         -DE/DX =    0.0                 !
 ! D8    D(3,7,8,5)           -179.9992         -DE/DX =    0.0                 !
 ! D9    D(3,7,8,6)            -59.9991         -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------
 GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

NH3BH3 Frequency

NH3BH3 Frequency [NH3BH3 Frequency] [NH3BH3 Frequency D space]
File Name SW_NH3BH3_freq
File Type .log
Calculation Type FREQ
Calculation Method RB3LYP
Basis Set 6-31G(d,p)
Change 0
Spin Singlet
E(RB3LYP) -83.22468906 a.u.
RMS Gradient Norm 0.00000024 a.u.
Imaginary Freq 0
Dipole Moment 5.5646 Debye
Point Group C1
Job cpu time: 0 days 0 hours 0 minutes 28.0 seconds.
 NH3BH3 Frequency 
 Low frequencies ---   -3.1658   -2.5379    0.0014    0.0015    0.0015    1.8917
 Low frequencies ---  263.4226  632.9765  638.4394

NH3BH3

Association Energy

Association Energy of NH3+BH3->NH3BH3

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

E(NH3)= -56.55776863 a.u.

E(BH3)= -26.61532364 a.u.

E(NH3BH3)= -83.22468906 a.u.

then still in AU compute the energy difference and report this on your wiki ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] = -83.22468906-[(-26.61532364)+(-56.55776863)]= -0.05159679 a.u.

the final step is to convert the energy difference from AU to kJ/mol

1 a.u. = 1 hartree = 2625.50 KJ/mol

ΔE=-0.0516 a.u. *2625.50 kJ/mol = -135.47 = KJ/mol

So the dissociation energy is +135.47 KJ/mol, endothermic dissociation. this number tells us the association energy for combinging a molecule of NH3 with one of BH3, conversely it is also the dissociation energy!

Week 2: Project: Ionic Liquids: Designer Solvents

Part 1: Comparison of selected 'onium' cations'

Optimisation and frequency of [N(CH3)4]+, [P(CH3)4]+ and [S(CH3)4]+

Optimisation and frequency of [N(CH3)4]+, [P(CH3)4]+ and [S(CH3)3]+
onium cations [N(CH3)4]+ [P(CH3)4]+ [S(CH3)4]+
File Name SW_[N(CH3)4]+_OPT_freq SW_[P(CH3)4]+_OPT_freq3 SW_[S(CH3)3]+_OPT_freq
File Type .log .log .log
Calculation Type FREQ FREQ FREQ
Calculation Method RB3LYP RB3LYP RB3LYP
Basis Set 6-31G(d,p) 6-31G(d,p) 6-31G(d,p)
Change 1 1 1
Spin Singlet Singlet Singlet
E(RB3LYP) (a.u.) -214.18127521 -500.82700333 -517.68325777
RMS Gradient Norm (a.u.) 0.00004006 0.00001637 0.00004777
Imaginary Freq 0 0 0
Dipole Moment (Debye) 0.0004 2.8852 0.9653
Point Group C1 C1 C1
Job cpu time 7 minutes 31.2 seconds. 7 minutes 12.1 seconds. 3 minutes 39.2 seconds.
IR Spectrum
Log file [[N(CH3)4+ ]] [[P(CH3)4+ ]] [[S(CH3)3+ ]]
D Space file [N(CH3)4+]] [[P(CH3)4+]] [[S(CH3)3+]]

Optimisation of [N(CH3)4]+

 
         Item               Value     Threshold  Converged?
 Maximum Force            0.000111     0.000450     YES
 RMS     Force            0.000028     0.000300     YES
 Maximum Displacement     0.001413     0.001800     YES
 RMS     Displacement     0.000314     0.001200     YES
 Predicted change in Energy=-1.051115D-07
 Optimization completed.
    -- Stationary point found.

Frequency of [N(CH3)4]+

 
 Low frequencies ---  -19.1188   -9.8202   -0.0009   -0.0006   -0.0001   21.7729
 Low frequencies ---  180.8192  277.3212  288.7343

Optimisation of [P(CH3)4]+

 
         Item               Value     Threshold  Converged?
 Maximum Force            0.000031     0.000450     YES
 RMS     Force            0.000012     0.000300     YES
 Maximum Displacement     0.000856     0.001800     YES
 RMS     Displacement     0.000253     0.001200     YES
 Predicted change in Energy=-3.411912D-08
 Optimization completed.
    -- Stationary point found.

Frequency of [P(CH3)4]+

 Low frequencies ---  -18.0294   -4.5198   -0.0036   -0.0032    0.0009   14.5481
 Low frequencies ---  153.7212  183.3695  191.3300

Optimisation of [S(CH3)3]+

         Item               Value     Threshold  Converged?
 Maximum Force            0.000158     0.000450     YES
 RMS     Force            0.000050     0.000300     YES
 Maximum Displacement     0.000943     0.001800     YES
 RMS     Displacement     0.000280     0.001200     YES
 Predicted change in Energy=-2.620616D-07
 Optimization completed.
    -- Stationary point found.

Frequency of [S(CH3)3]+

 Low frequencies ---  -29.1030  -19.8918   -0.0034   -0.0031   -0.0024   11.1429
 Low frequencies ---  159.6295  192.4985  205.8541

Molecular Orbital of [N(CH3)4]+, [P(CH3)4]+ and [S(CH3)4]+

Molecular Orbitals [N(CH3)4]+, [P(CH3)4]+ and [S(CH3)3]+
onium cations [N(CH3)4]+ [P(CH3)4]+ [S(CH3)4]+
File Name SW_[N(CH3)4]+_MO SW_[P(CH3)4]+_MO SW_[S(CH3)3]+_MO
File Type .log .log .log
Calculation Type SP SP SP
Calculation Method RB3LYP RB3LYP RB3LYP
Basis Set 6-31G(d,p) 6-31G(d,p) 6-31G(d,p)
Change 1 1 1
Spin Singlet Singlet Singlet
E(RB3LYP) (a.u.) -214.18127521 -500.82698242 -517.68325777
RMS Gradient Norm (a.u.) n/a n/a n/a
Imaginary Freq n/a n/a n/a
Dipole Moment (Debye) 0.0004 0.0021 0.9653
Point Group C1 C1 C1
Job cpu time 0 minutes 52.5 seconds 1 minutes 15.4 seconds 0 minutes 36.5 seconds
D Space file [N(CH3)4+]] [[P(CH3)4+]] [[S(CH3)3+]]
MO of [N(CH3)4]+
Energy Level [N(CH3)4]+ Description
MO6: E=-1.19645 comment
MO9: E=-0.92555 comment
MO10: E=-0.80747 text
MO14: E=-0.62247 text
MO21: E=-0.57933 text

Charge Distribution Analysis

Charge Distribution of [N(CH3)4]+, [P(CH3)4]+ and [S(CH3)3]+
onium cations [N(CH3)4]+ [P(CH3)4]+ [S(CH3)4]+
Ditribution with number
Ditribution with colour
Colour range -1.000 to 1.000 -1.000 to 1.000 -1.000 to 1.000
Description text text text


Questions:

Using the NBO charge analysis compare and contrast the charge distribution across this trio of cations. How can your results be rationalised? reminder: NBO charges not Mulliken! charges should be tabulated, it is difficult to compare charges visually via the images. however images are useful in a qualitative way and when you include images of the charge ensure your charge range is the same accross all the images. This can be set by manually altering the range on the charge bar. Ask a demonstrator if you need help! Using the NBO population analysis compare and contrast the relative contribution of the C and heteroatom to the C-X bond. How do your results relate to the charge distribution just studied? [NR4]+ (R=alkyl) is often depicted as shown, with the positive charge placed on the nitrogen centre. Based on your results for [N(CH3)4]+, discuss the validity of the traditional description. You should consider the following: What does the "formal" positive charge on the N represent in the traditional picture? On what atoms is the positive charge actually located for this cation?

Part 2: Influence of functional groups

Optimisation and frequency of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+

Optimisation and frequency of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+
cations [N(CH3)3(CH2OH)]+ [N(CH3)3(CH2CN)]+
File Name SW_[N(CH3)3(CH2OH)]+_OPT_freq_vtight SW_[N(CH3)3(CH2CN)]+_OPT_freq_vtight
File Type .log .log
Calculation Type FREQ FREQ
Calculation Method RB3LYP RB3LYP
Basis Set 6-31G(d,p) 6-31G(d,p)
Change 1 1
Spin Singlet Singlet
E(RB3LYP) (a.u.) -289.39470636 -306.39376141
RMS Gradient Norm (a.u.) 0.00000035 0.00000041
Imaginary Freq 0 0
Dipole Moment (Debye) 8.2355 8.6721
Point Group C1 C1
Job cpu time 21 minutes 54.9 seconds. 24 minutes 50.5 seconds.
IR Spectrum
Log file [[N(CH3)3(CH2OH)+ ]] [[N(CH3)3(CH2CN)+ ]]
D Space file [[N(CH3)3(CH2OH)+]] [[N(CH3)3(CH2CN)+]]

Optimisation of [N(CH3)3(CH2OH)]+

 
         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000002     YES
 RMS     Force            0.000000     0.000001     YES
 Maximum Displacement     0.000005     0.000006     YES
 RMS     Displacement     0.000001     0.000004     YES
 Predicted change in Energy=-2.728296D-13
 Optimization completed.
    -- Stationary point found.

Frequency of [N(CH3)3(CH2OH)]+

 
 Low frequencies ---   -9.6930   -7.6045   -4.7654   -0.0004   -0.0001    0.0005
 Low frequencies ---  130.7079  213.6972  255.6339

Optimisation of [N(CH3)3(CH2CN)]+

 
         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000002     YES
 RMS     Force            0.000000     0.000001     YES
 Maximum Displacement     0.000003     0.000006     YES
 RMS     Displacement     0.000001     0.000004     YES
 Predicted change in Energy=-3.560461D-13
 Optimization completed.
    -- Stationary point found.

Frequency of [N(CH3)3(CH2CN)]+

 
 Low frequencies ---   -4.7020   -4.2767   -0.0012   -0.0009   -0.0003    4.5253
 Low frequencies ---   91.5853  153.8209  211.2666

Molecular Orbital of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+

MO of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+
cations [N(CH3)3(CH2OH)]+ [N(CH3)3(CH2CN)]+
File Name SW_[N(CH3)3(CH2OH)]+MO SW_[N(CH3)3(CH2CN)]+MO_vtight
File Type .log .log
Calculation Type SP SP
Calculation Method RB3LYP RB3LYP
Basis Set 6-31G(d,p) 6-31G(d,p)
Change 1 1
Spin Singlet Singlet
E(RB3LYP) (a.u.) -289.39471123 -306.39377029
RMS Gradient Norm (a.u.) n/a n/a
Imaginary Freq n/a n/a
Dipole Moment (Debye) 2.1359 5.7642
Point Group C1 C1
Job cpu time 1 minutes 25.5 seconds. 1 minutes 38.8 seconds.
D Space file [[N(CH3)3(CH2OH)+]] [[N(CH3)3(CH2CN)+]]
HOMO LUMO comparison of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+
onium cations [N(CH3)4]+ [N(CH3)3(CH2OH)]+ [N(CH3)3(CH2CN)]+
LUMO
LUMO Level E22=-0.13301 E26=-0.12459 E28=-0.18183
HOMO
HOMO Level E21=-0.57933 E25=-0.48764 E27=-0.50047
Description text text

Charge Distribution Analysis

Charge Distribution of [N(CH3)3(CH2OH)]+ and [N(CH3)3(CH2CN)]+
onium cations [N(CH3)3(CH2OH)]+ [N(CH3)3(CH2CN)]+
Ditribution with number
Ditribution with colour
Colour range -1.000 to 1.000 -1.000 to 1.000
Description text text

Reference

1. L. C. Allen, J. Am. Chem. Soc., 1989, 111:9003

2. Kagaku Benran, CRC Handbook of Chemistry and Physics, 87th Edition, 1984, 2, 649–661