Study of the azo-hydrazone tautomeric equilibrium by electronic spectroscopy and quantum chemistry. II. HMO calculations

Abstract

Experimental data obtained in Part I of this work for p-hydroxy and p-amino derivatives of four arylazo compounds with different fused ring systems were correlated with some indices calculated by the simple HMO quantum chemical method in relation to the π-electron structure of the azo and hydrazone tautomers of the compounds studied. Mental fragmentation and the related stability of the systems expressed by Julg’s aromaticity indices of the hydrocarbon fragments appeared to be basically different for the two tautomers.