Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 20. Complexation of carbon–metal triple bonds with low-valent metal species; crystal structures of the bimetal complexes [CrW(µ-CC6H4Me-4)(CO)4(η-C5H5)(η-C6Me6)] and [CoW(µ-CC6H4Me-4)(CO)3(η-C5H5)(η-C5Me5)]

Abstract

A series of bimetal complexes [MW(µ-CR)(CO)₂(L_n)(η-C₅H₅)][R = C₆H₄Me-4; ML_n= Cr(CO)₂(η-C₆Me₆), Mn(CO)₂(η-C₅H₄Me), Re(CO)₂(η-C₅H₅), Co(CO)(η-C₅Me₅), Rh(CO)(η-C₉H₇)(C₉H₇= indenyl), lr(CO)(η-C₉H₇), and Ir(CO)(acac)(acac = acetylacetonate)] have been prepared from [W(CR)(CO)₂(η-C₅H₅)] and [Cr(CO)₂(thf)(η-C₆Me₆)](thf = tetrahydrofuran), [M(CO)₂(thf)(C₅H₄R′)](M = Mn, R′= Me; M = Re, R′= H), [Co(CO)₂(η-C₅Me₅)], [M(CO)₂(η-C₉H₇)](M = Rh or Ir), and [Ir(acac)(CO)₂], respectively. The compounds [RhW(µ-CMe)(CO)₃(η-C₅H₅)(η-C₉H₇)] and [MoRh(acac)(µ-CMe)(CO)₃(η-C₅H₅)] have also been obtained from related reactions. The spectroscopic data (i.r. and n.m.r.) for the new compounds are reported and discussed. The structures of the species [CrW(µ-CR)(CO)₄(η-C₅H₅)(η-C₆Me₆)], (1) and [CoW(µ-CR)(CO)₃(η-C₅H₅)(η-C₅Me₅)](4) have been established by _X-ray diffraction, and reveal an interesting distinction between (1) and (4). For both structures the metal–metal bond is bridged by a CC₆H₄Me-4 group and is semi-bridged by a CO ligand, but whereas in (4) it is one of the CO ligands on the W atom which semi-bridges to Co, in (1) it is a CO ligand on the Cr atom which semi-bridges to W. Reasons for this are discussed. In both structures the cyclic ligands bonded to the metal atoms are in a trans configuration with respect to the [graphic omitted] plane.