Role of Spin−Orbit Coupling and Symmetry in Triplet Carbenic Addition Chemistry

Abstract

The spin−orbit coupling parts in the effective one-electron Hamiltonian operator, with the inclusion of symmetry, have been used to formulate mechanisms based on the Shaik and Epiotis theory in triplet reactions for the radiationless decay of triplet complexes to singlet ground state products. This has been applied to investigate the stereochemical behavior of additions of triplet carbenes to olefins. It is shown that triplet carbene−olefin complexes can be classified according to the number and the direction of the atomic orbital rotations required to maximize spin−orbit coupling and simultaneously maintain the intermolecular binding, from which it may produce different stereoisomers. It is suggested that six spin-inversion reaction mechanisms produce geometric isomers. It is found that, as a direct of the different symmetries of the three sublevels of the triplet state (Tx, Ty, Tz) and their comparable spin-orbit coupling expressions, the triplet carbene could add to olefins nonstereospecifically. Never...