Theoretical investigations on the nature of intramolecular interactions

A previously developed energy-decomposition scheme in terms of quasiclassical, interference and charge-transfer interactions, which is intended as a tool for the analysis of HF-SCF, closed shell, single determinant calculations, is applied to the study of the anomeric effect. Synclinical and antiperiplanar conformations of XCH2OH molecules, with X = -CH3, -NH2 (t, g+, g-), -OH (t, g+, g-), -F have been analysed. It was found that the anomeric effect in these molecules is mainly due to the effect of substituent electronegativity on the CO-CX destructive interference interaction. Contributions from the quasiclassical and charge-transfer energy were found to be less important.