Model calculations of chemical interactions. Part 1.—Intramolecular interactions and rotational barriers

Abstract

A new procedure is introduced for the analysis of the effects of intramolecular interactions. Based on the most intuitive chemical picture of the energy differences between conformers, the procedure leads to explanations in terms of interactions between chemically meaningful subsystems into which the molecule can be conceptually partitioned, yet avoiding the concepts of antibond orbitals and bond–antibond interactions of the BO model. Use is made of the ab initio approximation with a minimal basis set of symmetrically orthogonalized hybrid AOs. Ethane, methylamine, methanol, propene, butadiene, glyoxal, hydrazine and hydroxylamine have been chosen as test molecules for the study of internal rotation.