User:Jt2010

3rd Year Computational Lab

Module 2: Hunt

BH₃

Link to BH₃ Optimization Analysis:

Summary containing all the information required and the basis set used for the calculation:

test molecule

This is the item information which gives that the optimization worked successfully.

                                              
        Item               Value     Threshold  Converged?
 Maximum Force            0.000019     0.000450     YES
 RMS     Force            0.000011     0.000300     YES
 Maximum Displacement     0.000143     0.001800     YES
 RMS     Displacement     0.000086     0.001200     YES
 Predicted change in Energy=-3.091865D-09
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1944         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.1944         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.1944         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.0095         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              119.9953         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              119.9953         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)            180.0            -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------

Bonds in this context can be defined as when total energy reaches an optimum and the gradient evens out. In this case this happens when the total energy = -26.24 au

BH₃_opt_631g

Link to Optimization Analysis:

File:BH3 OPT 2.LOG

The summary for the BH3 molecule which has been optimized using a better basis set:

test molecule

Item Table:

Item               Value     Threshold  Converged?
 Maximum Force            0.000152     0.000450     YES
 RMS     Force            0.000080     0.000300     YES
 Maximum Displacement     0.001032     0.001800     YES
 RMS     Displacement     0.000879     0.001200     YES
 Predicted change in Energy=-2.705532D-07
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.1922         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.1922         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.1924         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              120.1049         -DE/DX =   -0.0002              !
 ! A2    A(2,1,4)              119.9476         -DE/DX =    0.0001              !
 ! A3    A(3,1,4)              119.9476         -DE/DX =    0.0001              !
 ! D1    D(2,1,4,3)            179.9289         -DE/DX =    0.0001              !
 --------------------------------------------------------------------------------

Difference in energy between 3-21G optimized and 6-31G(d,p)difference = 0.24512924

However the difference in energy can not be compared directly as different basis sets were used.

B-H Bond Length: 1.19221 armstrong

H-B-H Bond Angle: 120.10486 degrees

TlBR3

Link to Optimization Analysis:

File:TIBR3 OPT3.LOG

D-space Link: http://hdl.handle.net/10042/20912

TIBR3 molecule summary which has been optimized using HCP.

test molecule

   Item               Value     Threshold  Converged?
 Maximum Force            0.000002     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000022     0.001800     YES
 RMS     Displacement     0.000014     0.001200     YES
 Predicted change in Energy=-6.084134D-11
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  2.651          -DE/DX =    0.0                 !
 ! R2    R(1,3)                  2.651          -DE/DX =    0.0                 !
 ! R3    R(1,4)                  2.651          -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                 !
 --------------------------------------------------------------------------------

Tl-Br Bond Length: 2.65095 Armstrong

Br-Tl-Br Bond angles: 120.00000 degrees

BBR₃

Link to Optimization Analysis:

File:BBR3 OPT.LOG

Summary:

test molecule

Item               Value     Threshold  Converged?
 Maximum Force            0.000035     0.000450     YES
 RMS     Force            0.000020     0.000300     YES
 Maximum Displacement     0.000144     0.001800     YES
 RMS     Displacement     0.000093     0.001200     YES
 Predicted change in Energy=-6.219588D-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)                  1.934          -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              119.9984         -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              119.9984         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              120.0033         -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)           -180.0018         -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------

B-Br Bond Length: 1.93401 Armstrong

Br-B-Br Bong Angles: 120.00020 degrees

Compare BH₃, BBr₃ and TIBr₃

Compare Molecules
	BH₃	TIBr₃	BBr₃
Bond Length (Armstrong)	1.19221	2.65095	1.93401
Bond Angle (degrees)	120.10486	120.00000	120.00020

From the data shown, it can be seen that the molecules which have the substituent ligands as Br atoms have much larger bong lengths. This is mainly due an increase in size of the ligand from H to Br, which increases the steric repulsion. Br and H are different is size and properties, however they both need only one more electron to complete their outer shell of electrons. In this respect they usually form single bonds.

When we change the central atom from B-Tl it can be seen that the bond angle is much more stable at 120.00000 degrees. The reason for this extra stabilization is that TI is a much larger central atom and as such the ligands have more space to attach to the central atom, so can optimize at better angles.

Tl and B are similar in that they are in the same group and as such prefer to form 3 bonds in the trigonal planar arrangement. However Tl is much larger than B and this allows more space for the ligands, so the steric repulsions will be less and the overall energy of the molecule will be lower and as such much more stable.

Bonding in Guassview

The bonding in Guassview sometimes does not draw bonds where we would normally expect them to be. The reason for this is not because they do not exist but because the bond distance exceeds some pre-defined value and as such the bonds are not drawn in by the program. As such the bond exists but is not represented by a line.

A bond is formed when the molecule is optimized and the bonds can be formed. Only when the ligands are in their correct positions and distances from each other can bonds be formed and as such in this instance a bond can form when the molecule is optimized and the optimization leads to a decrease in total energy.

BH₃ Frequency Calculations

Frequency Analysis File: File:JAMES BH3 FREQ OPT.LOG

test molecule

Summary:

Low frequencies ---   -5.4856   -0.0012   -0.0009   -0.0005    4.3595   15.7526
 Low frequencies --- 1163.0070 1212.9841 1213.4664

Vibrations in BH₃
Number	Form of Vibration	Frequency (Hz)	Intensity	symmetry D3h point group
1	There is wagging motion, with the ligands going in a different direction to the central atom	1163.01	92.5484	A₂'
2	Vibration where 2 Hydrogen atoms are vibrating towards each other. All other atoms remain as stable as possible.	1212.98	14.0547	E'
3	2 Hydrogen atoms vibrating in a clockwise motion, 1 Hydrogen in a anti clockwise motion. These vibrations are all the the planar plane.	1213.47	14.0660	E'
4	Fixed central atom. The Hydrogen's all vibrating in and out in phase, all in the XY plane.	2582.16	0.0002	A₁'
5	Hydrogen's all vibrating in and out from the center. 1 Hydrogen vibrating out of phase (greater intensity) relative to the other Hydrogen's. .	2715.10	126.3759	E'
6	1 Hydrogen in a fixed position. The other 2 Hydrogen's vibrating in and out, out of phase and in the xy Plane.	2715.54	126.2829	E'

Computed IR Spectrum of the molecule:

From the spectrum it can be seen that there are only 3 peaks when there should be 6 peaks. The reason for less peaks in the IR spectrum is because the frequency of the vibrations are too low in intensity. Another reason is that only vibrations which cause a change in the dipole moment are observed, and in this case only 3 of the vibrations cause a change in the dipole moment.

TlBr₃ Frequency Analysis

Frequency analysis file:

File:James TIBR3 opt freq.log

D-space Link: http://hdl.handle.net/10042/20914

Summary:

  Low frequencies ---   -3.4213   -0.0026   -0.0004    0.0015    3.9367    3.9367
 Low frequencies ---   46.4289   46.4292   52.1449

Spectrum:

Vibrations in TIBr3
Number	Frequency (Hz)	Intensity	symmetry D3h point group
1	46.43	3.6867	E'
2	46.43	3.6867	E'
3	52.14	5.8466	A₂'
4	165.27	0.0000	A₁'
5	210.69	25.4830	E'
6	210.69	25.4797	E'

BH₃ and TlBr₃ Compare Frequencies

Table of Frequencies:

Compare Vibration Frequencies
Number	Frequency (Hz) BH3	Frequency (Hz) TlBr3
1	1163.01	46.43
2	1212.98	46.43
3	1213.47	52.14
4	2582.16	165.27
5	2715.10	210.69
6	2715.54	210.69

The big difference in vibrating frequencies for BH₃ and TlBr₃ indicates that the BH3 molecule vibrates much more compared to the TlBr₃ molecule. As such the frequency of the absorbed radiation for the vibrations of the BH₃ molecule is bigger than that for the TlBr₃ molecule. This is due to the fact that the TlBr₃ molecules are much heavier and therefore vibrate much less.

There has been no reordering of the modes and this is due to the fact that although the ligands are different the structure and bonding is similar and such they vibrate in the same way. The spectra are similar in that only 3 peaks are observed in the spectrum. For TlBr₃ there is a little bit of overlap and this is due to the smaller vibrations.

The reason why the A1' and E' modes lie higher in energy is due to the vibration causing a greater change in dipole moment and also causing some steric clashing. This is turn means that the mode will be higher in energy to achieve this vibration.

You must use the same method and basis set for optimization and frequency analysis calculations, as they provide the conditions, criteria and assumptions for that calculation. If the same method and basis set were not used then the optimization would not directly correspond with the frequency analysis and it would not be a true calculation for the molecule.

The reason for carrying out frequency analysis is so that we can work out not only how many modes there are, but how these vibrations actually happen, there frequency and their intensities. Therefore from this we can work out some properties of the molecule and compare it to others.

The low frequencies represent the 3N-6 vibrational frequencies of a molecule. They represent the vibrations of the central atom and that of the ligand.^[1]

Molecular Orbitals

Population Analysis:

File:BH3 OPT 3 NBO.LOG

D-space Link: http://hdl.handle.net/10042/20924

Summary:

NBO from calculation:

MO Diagram:

From the diagram above, it can be seen that there is no significant differences between the real and LCAO MOs. This means that the accuracy and usefulness of qualitative MO theory is useful in determining the electron density distribution of orbitals.

NH₃

Optimization analysis:

File:NH3 OPT 31G.LOG

test molecule

Summary:

 Item               Value     Threshold  Converged?
 Maximum Force            0.000013     0.000450     YES
 RMS     Force            0.000009     0.000300     YES
 Maximum Displacement     0.000882     0.001800     YES
 RMS     Displacement     0.000401     0.001200     YES
 Predicted change in Energy=-1.228456D-08
 Optimization completed.
    -- Stationary point found.
                           ----------------------------
                           !   Optimized Parameters   !
                           ! (Angstroms and Degrees)  !
 --------------------------                            --------------------------
 ! Name  Definition              Value          Derivative Info.                !
 --------------------------------------------------------------------------------
 ! R1    R(1,2)                  1.0059         -DE/DX =    0.0                 !
 ! R2    R(1,3)                  1.0059         -DE/DX =    0.0                 !
 ! R3    R(1,4)                  1.0059         -DE/DX =    0.0                 !
 ! A1    A(2,1,3)              116.161          -DE/DX =    0.0                 !
 ! A2    A(2,1,4)              116.1555         -DE/DX =    0.0                 !
 ! A3    A(3,1,4)              116.155          -DE/DX =    0.0                 !
 ! D1    D(2,1,4,3)           -142.0359         -DE/DX =    0.0                 !
 --------------------------------------------------------------------------------

Frequency Analysis:

File:JAMES NH3 FREQ.LOG

Summary:

Frequencies:

Low frequencies ---  -39.1033  -36.6023  -14.8553   -0.0018   -0.0016    0.0010
 Low frequencies ---  459.9351 1681.1325 1681.2065

Population Analysis:

File:NH3 POPULATION ANALYSIS.LOG

NH₃ Charge Distribution

Charge distribution by color:

Charge Limits are: -0.865 to 0.865

Charge Distribution by numbers:

The NBO charges for Nitrogen are ).865 and the NBO charge for Hydrogen is 0.288

Association Energies: Ammonia-Borane

Optimization Analysis:

File:NH3BH3 OPT.LOG

test molecule

Summary:

Item               Value     Threshold  Converged?
 Maximum Force            0.000121     0.000450     YES
 RMS     Force            0.000057     0.000300     YES
 Maximum Displacement     0.000508     0.001800     YES
 RMS     Displacement     0.000294     0.001200     YES
 Predicted change in Energy=-1.611642D-07
 Optimization completed.
    -- Stationary point found.

Frequency Analysis:

File:NH3BH3 FEQ.LOG

Summary:

 Low frequencies ---   -0.0012   -0.0009   -0.0004   18.4289   23.8632   41.9195
 Low frequencies ---  266.4197  632.3169  639.8513

Energies:

E(NH₃) = -56.53188619 AU

E(BH₃) = -26.61532371 AU

E(NH₃BH₃) = -83.22469031 AU

Energy difference = E(NH₃BH₃)-[E(BH₃)+E(NH₃)]

Energy difference = -83.22469031 + 83.1472099

Energy difference = -0.07748041 AU

Energy difference = -203.4246935 KJ/mol^[2]

Ionic Liquids, designer solvents Part 1: Comparison of Selected 'Onium' Cations

[N(CH₃)₄]⁺

Optimization analysis:

File:N(CH3)4 opt HCP.log

D-Space Link: http://hdl.handle.net/10042/20929

Summary:

test molecule

Item               Value     Threshold  Converged?
 Maximum Force            0.000074     0.000450     YES
 RMS     Force            0.000017     0.000300     YES
 Maximum Displacement     0.000605     0.001800     YES
 RMS     Displacement     0.000161     0.001200     YES
 Predicted change in Energy=-4.648848D-08
 Optimization completed.
    -- Stationary point found.

Frequencies:

Frequency Analysis:

File:N(CH3)4 freq HCP.log

D-space Link: http://hdl.handle.net/10042/20933

Summary:

Low frequencies ---  -13.0246    0.0006    0.0007    0.0008    6.1520   11.9059
 Low frequencies ---  179.8775  278.8635  285.6949

[P(CH₃)₄]⁺

Optimization Analysis:

File:P(CH3)4 opt HCP.log

D-space Link: http://hdl.handle.net/10042/20931

Summary:

test molecule

 Item               Value     Threshold  Converged?
 Maximum Force            0.000148     0.000450     YES
 RMS     Force            0.000033     0.000300     YES
 Maximum Displacement     0.000960     0.001800     YES
 RMS     Displacement     0.000313     0.001200     YES
 Predicted change in Energy=-1.853525D-07
 Optimization completed.
    -- Stationary point found.

Frequencies:

Frequency Analysis:

File:P(CH3)4 freq HCP.log

D-space Link: http://hdl.handle.net/10042/20934

Summary:

Low frequencies ---  -16.6401   -0.0030   -0.0019   -0.0014    4.1223   16.1794
 Low frequencies ---  153.2905  183.0706  190.9459

[S(CH₃)₄]⁺

Optimization Analysis:

File:S(CH3)3 opt HCP.log

D-space Link: http://hdl.handle.net/10042/20931

Summary:

test molecule

Item               Value     Threshold  Converged?
 Maximum Force            0.000040     0.000450     YES
 RMS     Force            0.000009     0.000300     YES
 Maximum Displacement     0.000531     0.001800     YES
 RMS     Displacement     0.000155     0.001200     YES
 Predicted change in Energy=-1.318119D-08
 Optimization completed.
    -- Stationary point found.

Frequencies:

Frequency Analysis:

File:S(CH3)3 freq HCP.log

D-space: http://hdl.handle.net/10042/20936

Summary:

Low frequencies ---  -13.3190  -11.3800   -0.0025    0.0013    0.0015   22.9482
 Low frequencies ---  158.6053  194.1634  198.4824

MO's

Below are the MO's for [N(CH₃)₄]⁺:

The MO's have been produced through MO analysis on HCP with the additional keywords "Full NBO". Below are a set of 5 MO's which range from highly bonding down to highly anti-bonding.

- MO 1

In this MO, it can be seen that most of the molecule is bonding. As such the AO's have strong orbital overlap. There is very strong through space bonding overlap. Only one node is present in the center of the molecule. The MO is strongly de-localised.

- MO 5

In this view we can see that anti-bonding is starting to emerge in the MO's. As such the AO's have weak bonding overlap. Through space bonding is still happening in the MO, however this is also through space anti-bonding emerging. Nodes are present on each of the 4 carbons and the central atom. The MO is still de-localised.

- MO 12

In this MO it can be seen that there is just as much anti-bonding as there is bonding. Through space anti-bonding has now become quite large, however there is still alot of bonding overlap. Nodes will appear between in and out of phase electron density clouds. De-localisation is has started to become less obvious.

- MO 18

In this MO, it can be seen that anti-bonding interactions are beginning to dominate. As such the AO's have weak anti-bonding overlap. Through space anti-bonding is dominating with nodes between each of the different phased electron density clouds. The MO is weakly de-localised.

- MO 24

Very strong anti-bonding is seen in this MO. As such the AO's have strong anti-bonding overlap. Through space anti-bonding is very strong with large surface area of different phased electron clouds. The nodes will be between these different sheets of electron clouds. The Mo is very weakly de-localised.

NBO's

[N(CH₃)₄]⁺ D-Space Link: http://hdl.handle.net/10042/20939

[P(CH₃)₄]⁺ D-Space Link: http://hdl.handle.net/10042/20941

[S(CH₃)₄]⁺ D-Space Link: http://hdl.handle.net/10042/20942

[N(CH₃)₄]⁺

File: File:N(CH3)4 MO.log

Charge Range: -1.000 to 1.000

[P(CH₃)₄]⁺

File: File:P(CH3)4 MO.log

Charge Range: -1.000 to 1.000

[S(CH₃)₄]⁺

File: File:S(CH3)3 MO.log

Charge Range: -1.000 to 1.000

Compare Charge Densities
Number	[N(CH₃)₄]⁺	[P(CH₃)₄]⁺	[S(CH₃)₄]⁺
Charge on central atom	-0.295	1.667	0.917
Charge on Carbon	-0.483	-1.060	-0.846
Charge on Hydrogen	0.269	0.298	0.297 (0.279 for Hydrogens slightly further from Sulphur

From the table above, it can be sen that the Nitrogen atom is most electron rich whilst Phosphorus and Sulfur are electron deficient, with Phosphorus being more electron deficient than Sulfur. Nitrogen is most electron rich as it is a very electron-negative atom, and is more electronegative than Carbon. As such electron density is donated towards the Nitrogen which is why it has a negative charge density value.

For Phosphorus and Sulfur, Sulfur is more electron negative than Phosphorus and as such has a lower charge than Phosphorus. On top of that Sulfur is more electron negative than Carbon. As such it will be electron donating towards the Sulfur. As Phosphorus is less electron negative than Carbon it will be opposite in this case.

This is all reflected in the values for the carbon atom, where the Electron density is C(P)>C(S)>C(N). The reason for this is Phosphorus donates electron density to the carbons, whilst for Sulfur and Nitrogen this is the opposite way round with Nitrogen withdrawing the most electron density from the carbon atoms.

The same trend is seen for the Hydrogen atoms, however they are affected less due to distance. It should be noted though that for the Hydrogen's which are furthest from the Sulfur atom on [S(CH₃)₄]⁺ electron density on these hydrogen's is higher. This means that less electron density is being withdrawn by the Sulfur and it also shows that the Sulfur still has significant impact at 2 bond lengths distance. ^[3]

Compare and Contrast the charge contribution of the C and hetero atom to the C-X Bond.
	Number	[N(CH₃)₄]⁺	[P(CH₃)₄]⁺	[S(CH₃)₄]⁺
	Contribution of Carbon	( 33.65%) s( 20.76%)p 3.81( 79.07%)d 0.01( 0.16%)	( 59.56%)s( 25.24%)p 2.96( 74.68%)d 0.00( 0.08%)	( 48.67%)s( 19.70%)p 4.07( 80.16%)d 0.01( 0.14%)
	Contribution of Hetero atom	( 66.35%) s( 25.00%)p 3.00( 74.97%)d 0.00( 0.03%)	( 40.44%) s( 25.01%)p 2.96( 74.14%)d 0.03( 0.85%)	( 51.33%)s( 16.95%)p 4.86( 82.42%)d 0.04( 0.63%)

The results from the table above relate to the charge distribution just studied as from the table it is possible to see that the more positive charged the hetero atom the greater contribution from the Carbon atom towards the bond. This is in the order of C-P>C-S>C-N and from the charge distribution table we can see the positive P>S>N. From this trend it is possible to see how the 2 results relate.

[NR₄]⁺

Based on the results for [N(CH₃)₄]⁺, the description that there is a full positive charge placed on the Nitrogen is invalid. As from the table for charge distribution, we can clearly see there should be a slight negative charge on the Nitrogen atom, and the positive charge is actually distributed across all the Hydrogen atoms. However the reason why the positive charge is placed on the Nitrogen normally is for ease of depiction. It is the central point for where the excess charge is.

Ionic Liquids, designer solvents Part 2: Influence of Functional Groups

{N(CH₃)₃(CH₂OH)]⁺

Optimization Analysis:

File:N(CH3)3(CH2OH) opt HCP.log

D-space Link: http://hdl.handle.net/10042/20946

Summary:

test molecule

Item               Value     Threshold  Converged?
 Maximum Force            0.000008     0.000450     YES
 RMS     Force            0.000002     0.000300     YES
 Maximum Displacement     0.000422     0.001800     YES
 RMS     Displacement     0.000081     0.001200     YES
 Predicted change in Energy=-3.067229D-09
 Optimization completed.
    -- Stationary point found.

Frequencies:

Frequency Analysis:

File:N(CH3)3(CH2OH) freq HCP.log

D-space Link: http://hdl.handle.net/10042/20950

Summary:

Low frequencies --- -125.8305  -18.9294   -7.7264    0.0005    0.0006    0.0008
 Low frequencies ---    6.8058  124.4789  210.3464

{N(CH₃)₃(CH₂CN)]⁺

Optimization Analysis:

File:N(CH3)3(CH2CN) opt HCP.log

D-space: http://hdl.handle.net/10042/20948

Summary:

test molecule

Item               Value     Threshold  Converged?
 Maximum Force            0.000021     0.000450     YES
 RMS     Force            0.000005     0.000300     YES
 Maximum Displacement     0.001212     0.001800     YES
 RMS     Displacement     0.000292     0.001200     YES
 Predicted change in Energy=-1.366537D-08
 Optimization completed.
    -- Stationary point found.

Frequencies:

Frequency Analysis:

File:N(CH3)3(CH2CN) freq HCP.log

D-space Link: http://hdl.handle.net/10042/20951

Summary:

Low frequencies ---   -4.1918   -0.0003    0.0005    0.0007    6.2330   14.0866
 Low frequencies ---   91.1099  153.8131  210.7761

MO's and NBO's {N(CH₃)₃(CH₂OH)]⁺

MO Population Analysis:

File:N(CH3)3(CH2OH) MO HCP.log

Summary:

NBO

{N(CH₃)₃(CH₂OH)]⁺ D-space Link: http://hdl.handle.net/10042/20952

{N(CH₃)₃(CH₂CN)]⁺ D-space Link: http://hdl.handle.net/10042/20953

Charge Range: -1.000 to 1.000

MO's and NBO's {N(CH₃)₃(CH₂CN)]⁺

MO Population Analysis:

File:N(CH3)3(CH2CN) MO HCP.log

Summary:

NBO

Charge Range: -1.000 to 1.000

Compare charge Distribution {N(CH₃)₃(CH₂CN)]⁺ & {N(CH₃)₃(CH₂OH)]⁺

Compare Charge Densities
Number	{N(CH₃)₃(CH₂OH)]⁺	[N(CH₃)₃(CH₂CN)]⁺
Charge on central atom	-0.313	-0.289
Charge on O/N	-0.757	-0.186
Charge on adjacent Carbon	0.094	0.209

From what can be determined from the diagrams and table above, the OH is an electron donating group and he CN is an electron withdrawing group. The Oxygen atom has is a very electron negative group but has lone pairs which i can donate into the system. As such The electron negativity on the adjacent carbon is increased a lot. Also if we compare the value of the central atoms between {N(CH₃)₃(CH₂OH)]⁺ (-0.313) and [N(CH₃)₄]⁺ (-0.295). This proves that OH is an electron donating group as it has pushed electron density onto the central atom.

For [N(CH₃)₃(CH₂CN)]⁺, CN is a electron withdrawing and this can be seen as the central atom has had some electron density withdrawn from it.

Compare and Contrast HOMO and LUMO of [N(CH₃)₄]⁺, {N(CH₃)₃(CH₂CN)]⁺ & {N(CH₃)₃(CH₂OH)]⁺

Compare HOMO and LUMO
Number	[N(CH₃)₄]⁺	{N(CH₃)₃(CH₂OH)]⁺	[N(CH₃)₃(CH₂CN)]⁺
HOMO
LUMO
HOMO Energy	-0.57929	-0.46627	-0.50048
LUMO Energy	-0.13305	-0.11995	-0.18184

For the HOMO levels the shape of the MO's have not changed much for {N(CH₃)₃(CH₂CN)]⁺ & {N(CH₃)₃(CH₂OH)]⁺. However the shape is completely different for [N(CH₃)₄]⁺. This is because the different ligands which the other 2 molecules have. However we can see that they are all distinctly strong anti bonding. For the LUMO all the molecules exhibit strong anti-bonding.

The relative energies of the HOMO and LUMO have moved with the different molecules. This is due to the nature of the electron negative substituents. This has huge chemical impact as if the LUMO is lower in energy it will be easier for the system to accept an electron and therefore will be more reactive. If it is higher in energy then it will be harder to accept and electron and therefore less reactive. As such, {N(CH₃)₃(CH₂OH)]⁺ is more reactive than [N(CH₃)₄]⁺!, but [N(CH₃)₃(CH₂CN)]⁺ is less reactive.

References

↑ M. Wyart et al 2005 Europhys. Lett. 72 486
↑ Morrison, C. A. and M. M. Siddick (2004). "Dihydrogen Bonds in Solid BH3NH3." Angewandte Chemie International Edition 43(36): 4780-4782.
↑ Porezag, D. and M. R. Pederson (1999). "Optimization of Gaussian basis sets for density-functional calculations." Physical Review A 60(4): 2840-2847

[LazyDog-1] M. Wyart et al 2005 Europhys. Lett. 72 486

[HouseMat-2] Morrison, C. A. and M. M. Siddick (2004). "Dihydrogen Bonds in Solid BH3NH3." Angewandte Chemie International Edition 43(36): 4780-4782.

[LazyHorse-3] Porezag, D. and M. R. Pederson (1999). "Optimization of Gaussian basis sets for density-functional calculations." Physical Review A 60(4): 2840-2847

[1]

[2]

[3]

3rd Year Computational Lab

Module 2: Hunt

BH3

BH3_opt_631g

TlBR3

BBR3

Compare BH3, BBr3 and TIBr3

Bonding in Guassview

BH3 Frequency Calculations

TlBr3 Frequency Analysis

BH3 and TlBr3 Compare Frequencies

Molecular Orbitals

NH3

Association Energies: Ammonia-Borane

Ionic Liquids, designer solvents Part 1: Comparison of Selected 'Onium' Cations

[N(CH3)4]+

[P(CH3)4]+

[S(CH3)4]+

MO's

NBO's

[NR4]+

Ionic Liquids, designer solvents Part 2: Influence of Functional Groups

{N(CH3)3(CH2OH)]+

{N(CH3)3(CH2CN)]+

MO's and NBO's {N(CH3)3(CH2OH)]+

MO's and NBO's {N(CH3)3(CH2CN)]+

Compare charge Distribution {N(CH3)3(CH2CN)]+ & {N(CH3)3(CH2OH)]+

Compare and Contrast HOMO and LUMO of [N(CH3)4]+, {N(CH3)3(CH2CN)]+ & {N(CH3)3(CH2OH)]+

References

BH₃

BH₃_opt_631g

BBR₃

Compare BH₃, BBr₃ and TIBr₃

BH₃ Frequency Calculations

TlBr₃ Frequency Analysis

BH₃ and TlBr₃ Compare Frequencies

NH₃

[N(CH₃)₄]⁺

[P(CH₃)₄]⁺

[S(CH₃)₄]⁺

[NR₄]⁺

{N(CH₃)₃(CH₂OH)]⁺

{N(CH₃)₃(CH₂CN)]⁺

MO's and NBO's {N(CH₃)₃(CH₂OH)]⁺

MO's and NBO's {N(CH₃)₃(CH₂CN)]⁺

Compare charge Distribution {N(CH₃)₃(CH₂CN)]⁺ & {N(CH₃)₃(CH₂OH)]⁺

Compare and Contrast HOMO and LUMO of [N(CH₃)₄]⁺, {N(CH₃)₃(CH₂CN)]⁺ & {N(CH₃)₃(CH₂OH)]⁺