Relation between Pauling and Coulson Bond Orders in Benzenoid Hydrocarbons

Abstract

The relation between Pauling and Coulson bond orders in benzenoid hydrocarbons is examined. The carbon–carbon bonds of benzenoid hydrocarbons have to be classified into three classes, depending on the number of attached hydrogen atoms. Within each class the correlation between the bond orders is linear. The results can be used to rationalize the recently discovered correlation between the energy and electron contents of rings. An approximate expression for the total π-electron energy is also deduced.