Influence of unsaturated chromophore excitation on the feasibility and selectivity of adjacent σ bond cleavage

Abstract

The feasibility and selectivity of the cleavage of a σ bond adjacent to an unsaturated CX chromophore are analysed by qualitative theoretical and quantitative ab initio methods. The reasons why the nπ* states are best suited to the cleavage are clearly shown. In the case of asymmetrical systems selectivity is ordered by the relative weight of mixing between the n lone pair and the bonding σ molecular orbitals corresponding to the competing bonds.