Electron Configuration Analysis for Many-System Interactions. Electron Delocalization in Pyracylene, Acepleiadylene, and Dipleiadiene

Abstract

Abstract The method of electron configuration analysis for many-system interactions (ECAMSI) has been developed and applied to the π electronic structures of polycyclic molecules. The HMO-ECAMSI calculations have been carried out on acenaphthylene, pleiadiene, pyracylene, acepleiadylene, and dipleiadiene. Electron delocalization in the naphthalene core predominates in these molecules and remains unchanged from acenaphthylene to dipleiadiene; the central cross-linked π bond is not a small perturbation. There are four electron-delocalizing modes for the cyclic peripheral conjugation in acepleiadylene which give rise to an additional but appreciable delocalization, while the peripheral delocalization in pyracylene and dipleiadiene is almost completely depressed. The substituent effects on the delocalization have been predicted on the basis of the ECAMSI results and on the concept of the continuity-discontinuity of cyclic conjugation which has recently been developed.