A Dinitrogen Divanadium Complex Supported by a Trisamidophosphine Ligand

The reaction between tripodal trisamidophosphine ligand H₃PN₃^Ar and V(Mes)₃(THF) (Mes = mesityl) yields the vanadium(III) complex (PN₃^Ar)V (1) with an open site in the axial position, which could coordinate with THF, pyridine, and NH₃ to form the corresponding adducts (2—4). The vanadium(III) center is redox-active, as demonstrated by cyclic voltammetry methods and chemical oxidation or reduction. Notably, a novel dinitrogen divanadium complex with a bridging N₂ ligand, {K(THF)}₂{[PN₃^Ar]V}₂(μ-N₂) (6), was synthesized via treatment of 1 with 1 equivalent of potassium naphthalenide in THF under a N₂ atmosphere. The electronic structures and binding properties of 6 are evaluated and discussed based on its DFT calculations. Additionally, these vanadium complexes (1, 5, 6) can serve as catalysts for the conversion of N₂ into N(SiMe₃)₃ in the presence of reductants and Me₃SiCl.