On the Hall rule in the theory of benzenoid hydrocarbons

Abstract

In 1973, Hall noticed that the total π-electron energy (E) of isomeric benzenoid hydrocarbons is a linear function of the number of Kekule structures (K). Since then, this remarkable rule has been confirmed on a plethora of examples. Twenty years later, it was discovered that for large benzenoids (with nine or more hexagons) the E–K dependence is slightly curvilinear. We now elaborate a novel approach, describing and, to some extent, rationalizing these peculiar features of the E–K dependence. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 74: 627–632, 1999