Pyramidalized olefins: a DFT study of the homosesquinorbornene and sesquibicyclo[2.2.2]octene nuclei.

Density functional theory (B3LYP/6-31G*) was used to study a series of homosesquinorbornenes and sesquibicyclo[2.2.2]octenes. The compounds in which the two faces of the double bond are different are predicted to have a pyramidal double bond with butterfly bendings (psi) ranging from 1.8 to 17.9 degrees. The degree of pyramidalization of these central double bonds is greater in the homosesquinorbornenes than in the sesquibicyclo[2.2.2]octenes.