title: A tungsten complex containing a highly delocalized metal-ligand system.
abstract: Nucleophilic attack of (triphenylphosphonio)cyclopentadienide on the dichlorodiazomethane-tungsten complex trans-[BrW(dppe)(2)(N(2)CCl(2))]PF(6) [dppe is 1,2-bis(diphenylphosphino)ethane] results in C-C bond formation and affords the title compound, trans-[W(C(24)H(18)ClN(2)P)Br(C(26)H(24)P(2))(2)]PF(6) x 0.6CH(2)Cl(2). This complex, bis[1,2-bis(diphenylphosphino)ethane]bromido{chloro[3-(triphenylphosphonio)cyclopentadienylidene]diazomethanediido}tungsten hexafluorophosphate dichloromethane 0.6-solvate, contains the previously unknown ligand chloro[3-(triphenylphosphonio)cyclopentadienylidene]diazomethane. Evidence from bond lengths and torsion angles indicates significant through-ligand delocalization of electron density from tungsten to the nominally cationic phosphorus(V) centre. This structural analysis clearly demonstrates that the tungsten-dinitrogen unit is a powerful pi-electron donor with the ability to transfer electron density from the metal to a distant acceptor centre through an extended conjugated ligand system. As a consequence, complexes of this type could have potential applications as nonlinear optical materials and molecular semiconductors.
authors.affiliation: Department of Chemistry, University of Reading, Berks, England. h.m.colquhoun@rdg.ac.uk
authors.forename: Howard M
authors.initials: HM
authors.lastname: Colquhoun
authors.forename: Ann M
authors.initials: AM
authors.lastname: Chippindale
authors.forename: Yun Fu
authors.initials: YF
authors.lastname: Chan