Studies of transition-metal oxo- and nitrido-complexes. Part 4. Reactions of osmium tetraoxide with alkynes and dienes in the presence of tertiary amines

Abstract

Osmium tetraoxide (OsO4) reacts with alkynes R (R = C2H2, C2Ph2, PhC2H, or MeC2Ph) in the presence of tertiary amines L (L = pyridine or isoquinoline) to give trans-dioxo-osmium(VI) complexes [Os2O4(O4R)L4]. Reaction with dienes R (R = cyclo-octa-1,5-diene, 2,3-dimethylbuta-1,3-diene, or 4-vinylcyclohexene) in the presence of the same tertiary amines gives products [Os2O4(O4R)L4] and [OsO2(O2R)L2]. The structures of these complexes are discussed on the basis of their vibrational and 1H n.m.r. spectra. Hydrolysis of some of the complexes has been carried out and the organic products identified.