Condensation of triketones with tungsten hydrazido(2-) complexes derived from a dinitrogen complex: formation of mononuclear or dinuclear diazoalkane complexes

The tungsten hydrazido(2-) complex cis,mer-[WCl(2)(NNH(2))(PMe(2)Ph)(3)], readily derived from a dinitrogen complex cis-[W(N(2))(2)(PMe(2)Ph)(4)], reacted with 1,3,5-triketones RCOCH(2)COCH(2)COPh (R = Me, Ph) to give the diazoalkane complexes cis,mer-[WCl(2)(NN=CRCH(2)COCH(2)COPh)(PMe(2)Ph)(3)] (R = Me (3), Ph) via the condensation between the hydrazido(2-) ligand and one terminal carbonyl group in the triketone. By contrast, the reaction of the hydrazido(2-) complex cis,trans-[WCl(2)(NNH(2))(CO)(PMe(2)Ph)(2)] with PhCOCH(2)COCH(2)COPh resulted in the formation of a dinuclear mu-bis(diazoalkane) complex [WCl(2)(CO)(PMe(2)Ph)(2)(NN=CPhCH(2)COCH(2)CPh=NN)WCl(2)(CO)(PMe(2)Ph)(2)] (5). The structures of 3 and 5 in the solid state have been determined unequivocally by X-ray analysis. (C) 1999 Elsevier Science S.A. All rights reserved.