Tris(trimethylphosphine)cobalt(0) Compounds Containing Azaolefinic Ligands — Syntheses and Structures of Benzo[c]cinnoline and Phenylisocyanate Complexes

Abstract

Mononuclear cobalt(0) complexes Co(η2-azaolefin)(PMe3)3 (azaolefin = benzo[c]cinnoline (1), p-dimethylamino-phenyl(phenyl)diazene (2), 1/2 diazobenzene (3), bis(p-tolyl)diazene (4), bis(p-fluorphenyl)diazene (5), bis(p-trifluoromethyl-phenyl)diazene (6), phenylisocyanate (7)) are obtained from Co(cyclo-C5H8)(PMe3)3 by substitution of the olefin. X-ray crystal structure determinations of 1 and 7 show tetrahedral arrangements of ligands around the cobalt atom. By reaction with carbon monoxide carbonyl(phosphine)cobalt(0) complexes are formed. 7 catalyses the cyclotrimerization of phenylisocyanate, while with CoCl(PMe3)3 as a catalyst the cyclic dimer of phenylisocyanate is selectively formed. A convenient synthesis for CoCl(PMe3)3 is described.