The Hall rule in fluoranthene-type benzenoid hydrocarbons

Abstract

The applicability of the Hall rule (linear relation between the total ?-electron energy and the number of Kekul? structures) was investigated in the case of fluoranthene-type benzenoid hydrocarbons. It was found that the originnal Hall rule is not obeyed, but holds for sets of isomers with a fixed number of bay regions. For such groups of isomers, two apparently contradictory Hall-type rules were conceived, and it was found that both give almost identical numerical results.