General Rules for Constructing Hückel Molecular Orbital Characteristic Polynomials

Abstract

Graph-theoretical rules for evaluating the coefficients of an HMO characteristic polynomial, applicable to all conjugated systems, are presented. They represent an extension of earlier graph-theoretical formulas for conjugated hydrocarbons. The topological nature of the coefficients of the HMO characteristic polynomial can straightforwardly be understood by means of these rules. Moreover, they are essential to the graphical theory of aromaticity recently formulated by us. A quantitative expression is given between the same coefficients and the total π energy for heteroconjugated systems. © 1976, American Chemical Society. All rights reserved.