Molecular mechanics calculations on carbonyl compounds. III. Cycloketones

Molecular mechanics (MM4) calculations were carried out on cycloketones for ring sizes ranging from 4 to 11 carbon atoms. The MM4 relative energies for the various conformations of the cycloketones were compared to density functional theory (DFT) calculations (B3LYP/6-31G*), which were also carried out in this work. For small ring sizes (n = 4-6), calculated molecular geometries, dipole moments, moments of inertia, and vibrational spectra were compared to experimental data. The axial-equatorial energy differences in methyl-substituted cyclohexanones were also calculated by MM4 and compared to ab initio, DFT, and experimental results. The results of the MM4 studies on cycloketones showed significant improvement from those of MM3 calculations performed in parallel with the MM4 calculations. (C) 2001 John Wiley & Sons, Inc.