Further evidence for 1,2-hydrogen shift equilibria in the bis(η-cyclopentadienyl)methyltungsten system

Abstract

Trimethylphosphine reacts with [W(η-C₅H₅)₂(η-C₂H₄)Me]PF₆(1) to give [W(η-C₅H₅)₂(CH₂CH₂PMe₃)Me]PF₆(8) which decomposes thermally to [W(η-C₅H₅)₂(CH₂PMe₃)H]PF₆(9). Thermal equilibrium between (9) and [W(η-C₅H₅)₂(PMe₃)Me]PF₆(11) has been demonstrated. Methyldiphenylphosphine with [W(η-C₅H₅)₂(η-C₂H₄)Me]PF₆(1) gives the complex [W(η-C₅H₅)₂(CH₂PMePh₂)H]PF₆(10), then [W(η-C₅H₅)₂(PMePh₂)Me]PF₆(12). The products of the reaction of a 1:1 mixture of [W(η-C₅H₅)₂(η-C₂H₄)Me]PF₆(1) and the CD₃ analogue with PMe₂Ph show that intermolecular hydrogen/deuterium scrambling does not occur. Exchange of the PMe₂Ph group by PMe₃ has been shown in [W(η-C₅H₅)₂(CH₂PMePh₂)H]PF₆(10). A mechanism for the reactions involving reversible 1,2-hydrogen shift equilibria of the tungsten–methyl system is discussed.