Clar's valence structures of benzenoid hydrocarbons

Abstract

The properties of Clar's valence structures for unbranched catacondensed benzenoid systems have been considered. These molecules can be represented as caterpillar trees, i.e. ayclic graphs with side branches of length one only. The sextet polynomials of the benzenoids are simply related to the characteristic polynomials of corresponding caterpillar trees. Using the ‘ultimate pruning’ method we constructed the characteristic polynomials for several families of caterpillar trees. In some cases the characteristic polynomials are given in a compact form.