Stability of Trivalent Vanadium Alkyl and Hydride Supported by a Chelating Phosphinimido Ligand

Abstract

Reaction of [(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]VCl2 (1) with 2 equiv of MeLi yielded the corresponding trivalent vanadium derivative [(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]VMe2 (3). Subsequent hydrogenolysis afforded the dinuclear hydride complex {[(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]V}2(μ-H)2 (4), where reduction of the metal center to the divalent state had occurred. Hydrogenolysis of solutions of 1 previously treated with lower than stoichiometric amounts of MeLi afforded the two mixed-valent V(II)/V(III) hydrides {[(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]V}2(μ-Cl)2(μ-H) (6) and {[(Me3Si)NP(Ph)2C(H)P(Ph)2N(SiMe3)]V}2(μ-Cl)(μ-H)2 (7). Hydrolysis of the divalent 4 afforded the trivalent and dinuclear {[(Me3Si)NP(Ph)2C(H)P(Ph)2(μ-N)]V(OSiMe3)}2 (5), featuring migration of the Me3Si group from the N to the O atom of one incoming molecule of water.