Synthesis and X-ray crystal structures of imido and isodiazene complexes of vanadium, niobium and tantalum

Interaction of [M(NBu(t))(NHBu(t))(H(2)NBu(t))Cl-2](2), M = Nb, Ta, with five equiv. of Bu(t)NHLi gave {[M(NBu(t))(3)(NHBu(t))]Li-2}(2), M = Nb (2a), M = Ta (2b), which showed the presence of three different tert-butylimido groups and resisted further metallation. Interaction of MCl(5), M = Nb, Ta, with 1-amino-2,2,6,6-tetramethylpiperidine, C9H18NNH2, in the presence of Me(3)SiCl-Et(3)N gave (Et(3)NH)[M(C9H18N2)(2)Cl-4], M = Nb (3a), M = Ta (3b). A similar interaction with NH4VO3 gave low yields of [(C9H18N2)(2)(OSiMe(3))(2) V(mu-O)V(O)(OsiMe(3))(2)] (4). The X-ray crystal structures of (2a), (3b) and (4) have been determined. Copyright (C) 1997 Elsevier Science Ltd.