title: Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W2Cp2(μ-PCy2)(μ-CO)2](-).
abstract: Protonation of the title anion with [NH4]PF6 gave [W2Cp2(H)(μ-PCy2)(CO)2] (), which in solution exists as an equilibrium mixture of two isomers having either bridging (major) or terminal (minor) hydrides. Both molecules retain short intermetallic distances (ca. 2.54 Å), with the H-bridged isomer being almost 15 kJ mol(-1) more stable than the terminal one, according to density functional theory calculations. Further protonation with acids having weakly coordinating anions (BF4(-) or BAr'4(-); Ar' = 3,5-C6H3(CF3)2) yielded isomeric cations also displaying bridging and terminal hydride ligands ([W2Cp2(μ-H)(H)(μ-PCy2)(CO)2](+) and [W2Cp2(H)2(μ-PCy2)(CO)2](+)), with the latter being only slightly more energetic (by ca. 4 kJ mol(-1)). In contrast, protonation of with carboxylic acids yielded carboxylate-bridged derivatives [W2Cp2(μ-PCy2)(μ-O:O'-O2CR)(CO)2] [R = Ph, CF3] following from dihydrogen elimination. The title anion also reacted readily with metal-based electrophiles such as ClSnPh3 and [AuCl(PR3)] (R = (i)Pr, p-tol) to give the corresponding heterometallic clusters [W2Cp2(μ-PCy2)(μ-SnPh3)(CO)2] and [AuW2Cp2(μ-PCy2)(CO)2(PR3)], these having the added electrophile placed at the bridging position and formally retaining triple W-W bonds. The gold complexes, however, were rather unstable species decomposing spontaneously to give the tetranuclear clusters [Au2W2Cp2(μ-PCy2)(CO)2(PR3)2]X (W-W = 2.5803(6) Å and Au-Au = 2.8050(6) Å when R = (i)Pr and X = PF6), which could be prepared more conveniently by adding two equivalents of [AuCl(PR3)] to the anion, as expected. In contrast, reaction of the title anion with ClPbPh3 led to the formation of the phenyl-bridged complex [W2Cp2(μ-PCy2)(μ-Ph)(CO)2], following from the formal loss of PbPh2.
authors.affiliation: Departamento de Química Orgánica e Inorgánica/IUQOEM, Universidad de Oviedo, E-33071 Oviedo, Spain. garciavdaniel@uniovi.es mara@uniovi.es.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Alvarez
authors.forename: M Esther
authors.initials: ME
authors.lastname: García
authors.forename: Daniel
authors.initials: D
authors.lastname: García-Vivó
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Ruiz
authors.forename: M Fernanda
authors.initials: MF
authors.lastname: Vega