Valency-bond studies of some conjugated hydrocarbons—II Pentalene, and some preliminary results on heptalene

Abstract

Valency-bond studies of the still unknown molecule pentalene C8H6 in which the molecular symmetry may be either D2h or C2h show that a more stable molecule (lower ground state energy) is found for the lower symmetry, and that marked alternation of bond lengths occurs. The corresponding Penney-Dirac bond orders have been determined. Preliminary results for heptalene forecast a similar conclusion.