Abstract
Ab initio molecular orbital theory with the 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-311G(d,p), 6-311+G(d,p), 6-31G(2d), 6-311G(2d), and 6-311G(2d,p) basis sets have been used to calculate the conformational enthalpies (ΔH°), entropies (ΔS°), and free energies (ΔG°) of the axial and equatorial conformers of 2-methyl-, 3-methyl-, and 4-methyltetrahydro-2H-pyran (tetrahydropyran, oxacyclohexane, oxane) and methylcyclohexane (toluene). Although HF and MP2 generally gave higher conformational free energies (ΔG°) than the experimentally reported values, other MP2 calculations gave ΔG° values in excellent agreement with experimental results for methylcyclohexane [6-311G(d 311G(d,p)] and 3-methyltetrahydro-2H-pyran [6-31+G(d), 6-311+G(d,p)]. Consistent with solution studies, the MP2 calculations gave larger ΔG° values for 4-methyltetrahydro-2H-pyran than for methylcyclohexane.
| Original language | English |
|---|---|
| Pages (from-to) | 19-26 |
| Number of pages | 8 |
| Journal | Journal of Molecular Structure: THEOCHEM |
| Volume | 574 |
| Issue number | 1-3 |
| DOIs | |
| State | Published - 16 Nov 2001 |
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Keywords
- Ab initio molecular orbital theory
- Conformational free energies
- Methyl tetrahydro-2H-pyrans
- Methylcyclohexane (Toluene)
- Repulsive nonbonded interactions
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An ab initio molecular orbital theory study of the conformational free energies of 2-methyl-, 3-methyl-, and 4-methyltetrahydro-2H-pyran. / Freeman, F.; Kasner, Marc; Hehre, W. J.
In: Journal of Molecular Structure: THEOCHEM, Vol. 574, No. 1-3, 16.11.2001, p. 19-26.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - An ab initio molecular orbital theory study of the conformational free energies of 2-methyl-, 3-methyl-, and 4-methyltetrahydro-2H-pyran
AU - Freeman, F.
AU - Kasner, Marc
AU - Hehre, W. J.
PY - 2001/11/16
Y1 - 2001/11/16
N2 - Ab initio molecular orbital theory with the 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-311G(d,p), 6-311+G(d,p), 6-31G(2d), 6-311G(2d), and 6-311G(2d,p) basis sets have been used to calculate the conformational enthalpies (ΔH°), entropies (ΔS°), and free energies (ΔG°) of the axial and equatorial conformers of 2-methyl-, 3-methyl-, and 4-methyltetrahydro-2H-pyran (tetrahydropyran, oxacyclohexane, oxane) and methylcyclohexane (toluene). Although HF and MP2 generally gave higher conformational free energies (ΔG°) than the experimentally reported values, other MP2 calculations gave ΔG° values in excellent agreement with experimental results for methylcyclohexane [6-311G(d 311G(d,p)] and 3-methyltetrahydro-2H-pyran [6-31+G(d), 6-311+G(d,p)]. Consistent with solution studies, the MP2 calculations gave larger ΔG° values for 4-methyltetrahydro-2H-pyran than for methylcyclohexane.
AB - Ab initio molecular orbital theory with the 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-311G(d,p), 6-311+G(d,p), 6-31G(2d), 6-311G(2d), and 6-311G(2d,p) basis sets have been used to calculate the conformational enthalpies (ΔH°), entropies (ΔS°), and free energies (ΔG°) of the axial and equatorial conformers of 2-methyl-, 3-methyl-, and 4-methyltetrahydro-2H-pyran (tetrahydropyran, oxacyclohexane, oxane) and methylcyclohexane (toluene). Although HF and MP2 generally gave higher conformational free energies (ΔG°) than the experimentally reported values, other MP2 calculations gave ΔG° values in excellent agreement with experimental results for methylcyclohexane [6-311G(d 311G(d,p)] and 3-methyltetrahydro-2H-pyran [6-31+G(d), 6-311+G(d,p)]. Consistent with solution studies, the MP2 calculations gave larger ΔG° values for 4-methyltetrahydro-2H-pyran than for methylcyclohexane.
KW - Ab initio molecular orbital theory
KW - Conformational free energies
KW - Methyl tetrahydro-2H-pyrans
KW - Methylcyclohexane (Toluene)
KW - Repulsive nonbonded interactions
UR - http://www.scopus.com/inward/record.url?scp=0035900229&partnerID=8YFLogxK
U2 - 10.1016/S0166-1280(00)00757-0
DO - 10.1016/S0166-1280(00)00757-0
M3 - Article
VL - 574
SP - 19
EP - 26
JO - Journal of Molecular Structure: THEOCHEM
JF - Journal of Molecular Structure: THEOCHEM
SN - 0166-1280
IS - 1-3
ER -