| Abstract: | A novel graph-theoretical approach for ordering Kekulé valence structures of benzenoid hydrocarbons is presented. The approach involves the transformation of the Kekulé structures into the subspaces of their individual double bonds. The submolecules generated in this way H. Joela, Theor. Chim. Acta 39 , 241 (1975)] are ordered according to suitable connectivity indices. The resulting orders parallel those predicted from the so called Kekulé indices A. Graocvac, I. Gutman, M. Randi?, and N. Trinajst?, J. Am. Chem. Soc. 95 , 6267 (1973)]. A relation is thus illustrated between VB and MO theories. The method is new and allows the prediction of the relative stabilities of structures from purely combinatorial vent without resort to computer. |
