SYNTHESIS OF VANADIUM, NIOBIUM, AND TANTALUM SILYLIMIDO COMPLEXES AND REACTIVITY OF THEIR NITROGEN-SILICON BONDS

A series of group V transition-metal (trimethylsilyl)imido compounds has been synthesized in which the NSiMe3groups derive from hexamethyldisilazane. Reaction of MCl5with 2 equiv of NH(SiMe3)2produces [M(NSiMe3)Cl3(NH2SiMe3)]2(M = Nb, Ta). Pyridine and substituted pyridine adducts,(NSiMe3)Cl3L2(M = Nb, L = py, 4-Mepy, or 1/2 4,4'-Me2bpy; M = Ta, L = py), are prepared either by addition of ligand to the niobium dimer or by direct reaction of the metal halide with a mixture of hexamethyldisilazane and pyridine. Related vanadium (trimethylsilyl)imido compounds, V(NSiMe3)Cl3L2(L = 4-Etpy, 4-t-Bupy), are formed upon reaction of V(NSiMe3)Cl3with added ligand in pentane. The vanadium compounds undergo fast, stoichiometric loss of chlorotrimethylsilane, yielding the nitrido derivativeV(NCl2L2, in contrast to slow, incomplete elimination of ClSiMe3from the niobium and tantalum complexes. The reactivity of nitrogen-silicon bonds in silylimido ligands is discussed in light of these observations. © 1990, American Chemical Society. All rights reserved.