Chemistry of the Vanadium-Carbon sigma Bond. 2. Oxovanadium(IV) and Oxovanadium(V) Containing Metal-to-Carbon  Bonds

This is a report on the oxidation of organometallic vanadium(III) homoleptic compounds to the corresponding oxovanadium(V) derivatives by the use of either epoxides or molecular oxygen. Complex 1, [V(Mes)3(THF)], gave a clean deoxygenation of epoxides with the formation of [OV(Mes)3] (2). The reaction of 1 with 2 to give [{(Mes)3V}(μ2-O)] (3) exemplifies a general method for making (μ-oxo)vanadium(IV) dimers. Complex 3 undergoes a ligand redistribution reaction in the presence of coordinating solvents and with pyridine gave [(Mes)2VO(py)2] (4). Epoxides were good reagents for converting [V{μ2-C(Mes)NBut}3] (5) to [OV{μ2-C(Mes)NBut}3] (6) without affecting the VC bond. The thermal instability and reactivity of 6 is much higher than for 2. Reacting protic agents with 6 displaced a single iminoacyl to form [OV{μ2-C(Mes)NBut}2(OOCCH3)] (7) and [OV{μ2-C(Mes)NBut}2(Cl)] (8) from CH3COOH and HCl, respectively.