Geometrical isomerism in vinylmethylene

Abstract

The results of semiempirical MINDO/3 MO calculations on the lowest singlet and triplet states of methylene compare favourably with experimental data and ab initio SCF calculations including configuration interaction. The same methodology has been applied to vinylmethylene (lowest singlet and triplet states) and its stereoisomers. Their equilibrium geometries, singlet-tripleet, cis-trans and planar-perpendicular energy differences are reported. Their implications for the electronic structures of vinylmethylenes is also discussed.