Molybdenum (VI) Bisimidoaryl Phenoxide and Alkoxide Complexes : Molecular Structures of [Mo(NAr)2(OCMe2-2py)(CH2SiMe3)] and [{Mo(NAR)2Me(OMe}2]

Abstract

The synthesis and characterisation is reported of new, five-coordinate molybdenum(VI) bisimidoaryl complexes [Mo(NAr)2(O-N)(R)] [Ar = C6H3(iPr)2-2,6; O-N = 2-pyridyldiphenylmethoxide (a), 2-pyridyldimethylmethoxide (b), 8-quinolinolate (c); R = Cl, Me, CH2SiMe3] and the corresponding bisalkoxide (a, b) and bisphenolate [c, d = (OC6H4CH2NMe2-2)-] MoVI bisimidoaryl complexes [Mo(NAr)2(O-N)2]. These complexes can be formed by simple alcoholysis reactions between [Mo(NAr)2Cl2(DME)] and the appropriate alcohol in the presence of Et3N. The remaining chloride can be replaced by a methyl or trimethylsilylmethyl group by transmetallation with MeMgCl or LiCH2SiMe3. The solid state structure of [Mo(NAr)2(OCMe2-2-py)(CH2SiMe3)] (5) has been determined by single-crystal X-ray analysis. A similar synthetic procedure was used to synthesise and characterise [{Mo(NAr)2Me(OMe)}2] (7). The two methoxide ligands bridge between the two molybdenum(VI) nuclei. Compounds in which the ligand can form six-membered chelate rings {like [Mo(NAr)2(OC6H4CH2NMe2-2)2] (9) and analogues} are usually difficult to obtain in a pure form and yields are typically low.