Preparation and structure of alkylidene−osmium and hydride−alkylidyne−osmium complexes containing an n-heterocyclic carbene ligand

Abstract

The complex [(η6-p-cymene)OsCl(CHPh)(IPr)]OTf (1) releases the arene in acetonitrile at 40 °C. The resulting 12-valence-electron metallic fragment is trapped by the solvent to afford the tris(solvento) compound [OsCl(CHPh)(NCCH3)3(IPr)]OTf (2), which reacts with AgOTf in acetonitrile at room temperature to give the tetrakis(solvento) derivative [Os(CHPh)(NCCH3)4(IPr)](OTf)2 (3). In dichloromethane at 40 °C, the treatment of 1 with triisopropylphosphine and triphenylphosphine yields the unsaturated five-coordinate mixed phosphine−NHC hydride−alkylidyne−osmium species [OsHCl(CPh)(IPr)(PR3)]OTf (R = iPr (4), Ph (5)).