Cyclic Conjugation in Benzo-annelated Ovalenes

Abstract

The effect of small structural changes on the electronic properties of large benzenoid molecules is studied in the case of ovalene and its benzo-annelated derivatives. Two quantitative indicators of the intensity of cyclic conjugation in individual rings were used: the π-electron content and the energy effect. Most regularities observed can be rationalized by means of the classical Clar aromatic sextet theory, although a few second-order effects point towards the need to go beyond the Clar model.