Model calculations of chemical interactions. Part 2.—Intramolecular interactions and double-bond pyramidalization in polycyclic alkenes

Abstract

The origin of double-bond pyramidalization in alkenes asymmetrically incorporated into rigid cyclic systems has been investigated by means of an ab initio procedure using a minimal basis set of symmetrically orthogonalized hybrid AOs. A detailed study of bicyclo[2.1.0]pent-2-ene and norbornene led to the conclusion that the interactions between the π-AOs of the double bond and the σ-AOs involved in the σ-bonds at the allylic positions are largely dominant in controlling extent and direction of double-bond pyramidalization.