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.