Theoretical study of [10] and [12]annulenes

Abstract

Equilibrium geometries of various geometrical isomers of annulenes have been calculated by the quantum-chemical methods EHT, CNDO/2, MINDO/2, MINDO/3 and the method of empirical potentials. Automatic method of full optimization has been used for some [10]annulenes and all isomers of [12]annulene. The bond strengths and degree of delocalization have been determined from the bond overlap populations and the Wiberg indices. Relative stabilities of the isomers have been determined by comparison of the formation enthalpies calculated by MINDO/3, MINDO/2 and empirical potential methods. Strain energy has been calculated, and degree of aromaticity of the isomers has been characterized by several aromaticity indices.