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Methanol, CH3OH

Models were made using the best ab initio level of theory, which was 6311-G.  This is the best level because it is the biggest basis set for the molecule.  

Click below to view CH3OH bond lengths.  

methanol picture
Figure 1: CH3OH: (1)C, (2)O, (3)H, (4)H, (5)H, (6)H

Bond lengths of CH3OH were found using the Hamiltonians and three ab initio levels.  Bond lengths for atoms (1)C, (2)O, (3)H, (4)H, (5)H, (6)H in angstroms, , at the different levels of theory, see Figure 1.  Methanol had three literature bond lengths which were C-H 1.096 , C-O 1.427 , and O-H 0.956 .1
Atoms PM3 AM1 321-G 631-G 6311-G
1-2 1.394818 1.410427 1.440943 1.430507 1.428506
1-4 1.097026 1.118675 1.085102 1.083560 1.082426
1-5 1.093556 1.118997 1.078644 1.076815 1.075128
1-6 1.097016 1.118669 1.085122 1.083586 1.082428
2-3 0.948750  0.964087  0.965792 0.950207 0.946021


Click the button below to see CH3OH bond angles, H-C-H and H-O-C.
Click the button below to see CH3OH bond angles, O-C-H.
Bond angles for atoms (1)C, (2)O, (3)H, (4)H, (5)H, (6)H in degrees, , at the different levels of theory, see Figure 1.  Methanol had experimental bond angles of H-C-H 109.03 and H-O-C 108.87.1
Atoms PM3 AM1 321-G 631-G 6311-G
1-2-3 107.45 107.17 110.34 113.42 113.17
4-1-6 109.03 109.68 108.75 109.24 109.18
4-1-5 109.44 110.03 108.61 108.99 108.90
6-1-5 109.45 110.04 108.60 108.98 108.90
4-1-2 112.15 110.94 112.24 111.65 111.62
5-1-2 104.49 105.13 106.28 106.25 106.53
6-1-2 112.16 110.94 112.23 111.64 111.62

Click below to view the CH3OH HOMO orbital.   The HOMO orbital is the highest energy molecular orbital occupied by electrons.   From the model, it can be predicted how a molecule will react.   

Vibrational Frequencies
Click below to see the motion of the molecule at frequency 1116 cm-1. This contributes to ~1000 cm-1 peak in the IR spectrum. 2

Click below to see the motion of the molecule at frequency 1469 cm-1. This contributes to ~1400 cm-1 peak in the IR spectrum. 2
 
The next three frequencies contribute to the ~3000 cm-1 peak in the IR spectrum. 2 Click below to see the motion of the molecule at frequency 3156 cm-1
Click below to see the motion of the molecule at frequency 3211 cm-1
Click below to see the motion of the molecule at frequency 3305 cm-1

Click below to see the motion of the molecule at frequency 4043 cm-1. This contributes to ~3600 cm-1 peak in the IR spectrum. 2

Dipole moments at each level of theory for CH3OH.  Experimental 1.70 D.3
Theory Level Dipole (D)
PM3 1.621053
AM1 1.487285
321-G 2.121482
631-G 2.285451
6311-G 2.253251


References:
(1)  http://cccbdb.nist.gov/ .  Geometries. Experimental geometry data for a given species.  CH3OH.
(2)  http://webbook.nist.gov/. IR spectrum of CH3OH.
(3)  Lide, D. R. CRC Handbook of Chemistry and    Physics; CRC Press: Boca Raton, 1992.

HCl            Aniline
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