Ab initio calculations of conformational effects in saturated cyclic amines

Abstract In order to study the conformational equilibria of substituents at nitrogen in six-membered rings, the energies of three azacyclohexanes and their N -methylated derivatives were calculated using the 6-31G ∗ basis set. The results obtained were compared with experimental data and with previous calculations for those molecules. All our results are in agreement with experimental data. When molecular mechanics or ab initio calculations using smaller basis sets were applied in energy calculations of these polyazines, some discrepancies with the experimental results were observed. This work indicates that ab initio methods which include larger basis sets give better agreement with experimental data, and also give more reliable predictions in cases where no experimental data exist.