Homogeneous catalysis of olefin isomerisation. Part I. Reactions of trans-[2H2]ethylene catalysed by complexes of cobalt, ruthenium, rhodium, and palladium

Abstract

Reactions of trans-[²H₂]ethylene with solutions of CoHN₂(PPh₃)₃, RuHCl(PPh₃)₃, RuCl₂(PPh₃)₃, and of RhH(CO)-(PPh₃)₃ in benzene at 50° have been investigated. Redistribution of hydrogen isotopes in the ethylene occurred, leading eventually to a random distribution, the reaction proceeding via ethyl intermediates. Solutions of the hydrido-complexes were of comparable activity, and were more active than those of RuCl₂(PPh₃)₃. Hydrogen exchange was observed between deuterium atoms of the olefin and protium atoms in the ortho-positions of the triphenylphosphine ligands of RuHCl(PPh₃)₃.

A solution of PdCl₂(PhCN)₂ in benzene at 50° catalysed the conversion of trans-into cis-[²H₂]ethylene without simultaneous isotope redistribution. Routes by which this can occur are discussed.