Structure determination of a rhenium trimethylsilylmethyl acyl complex and hydrolysis of the carbon-silicon bond

Abstract

The X-ray crystal structure and reactivity of [ReO(C(O)CH2SiMe3)(CH2 SiMe3)2(PMe3)] are reported. The geometry about the rhenium atom can be described as trigonal bipyramidal with the equatorial plane defined by the acyl carbon, the oxo ligand and an alkyl methylene carbon. The Re-acyl interaction is best described as a composite of mono and dihapto acyl forms. [ReO(C(O)CH2SiMe3)(CH2SiMe3)2(PMe3)] reacts with potassium cyanide and excess water to yield K[ReO(CN)(C(O)CH3)(CH2SiMe3)2], a product of PMe3 substitution and C-Si bond hydrolysis. With rigorous exclusion of water only a PMe3 substitution reaction occurs. [ReO(C(O)CH2SiMe3)(CH2SiMe3)2(PMe3)] also reacts with water in the presence of AcO-, OCN-, SCN- or PMe3 to give the unstable hydrolysis product [ReO(C(O)CH3)(CH2SiMe3)2(PMe3)]. For the reactions involving AcO-, OCN- and SCN- a less than stoichiometric amount of base is needed to bring about the hydrolysis.