Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 24. Complexes of the pentamethylcyclopentadienylcopper group and the crystal structures of the compounds [CuPtW(µ-3CC6H4Me-4)(CO)2(PMe3)2(η-C5H5)(η-C5Me5)] and [CuRh2(µ-CO)2(η-C5Me5)3]

Abstract

Treatment of copper(I) chloride with Li(C₅Me₅) in tetrahydrofuran at low temperatures affords a reagent which is a useful source of the Cu(η-C₅Me₅) fragment in syntheses. The preparation of the compounds [CuW{µ-C(OMe)R}(CO)₅(η-C₅Me₅)], [Cu₂W(µ₃-CR)(CO)₂(η-C₅H₅)(η-C₅Me₅)₂], [CuPtW(η₃-CR)(CO)₂(PMe₃)₂(η-C₅H₅)(η-C₅Me₅)], [Cu₂PtW₂(µ₃-CR)₂(CO)₄(η-C₅H₅)₂(η-C₅Me₅)₂](R = C₆H₄Me-4), [CuPt(µ-PhC₂Ph)(PMe₃)₂(η-C₅Me₅)], and [CuRh₂(µ-CO)₂(η-C₅Me₅)₃] is described, and spectroscopic data (i.r. and n.m.r.) for the new species are reported and discussed. Single-crystal X-ray diffraction studies have been carried out on the compounds [CuPtW(µ₃-CC₆H₄Me-4)(CO)₂(PMe₃)₂(η-C₅H₅)(η-C₅Me₅)] and [CuRh₂(µ-CO)₂(η-C₅Me₅)₃]. In the former compound, the µ-CCuPtW core atoms adopt a butterfly configuration with an angle of fold of 90.6° between the C,W,Pt and C,W,Cu planes. The Cu ⋯ Pt separation [2.807(3)Å] implies little or no metal–metal bonding between these centres. The tungsten atom carries an η-C₅H₅ group and two CO ligands, one of which semi-bridges [W–C–O 162(2)°] the Pt–W bond [2.779(2)Å]. The C₅Me₅ ligand on copper is η⁵-bonded to the metal, and the Cu–W distance is 2.648(3)Å. The structure of [CuRh₂(µ-CO)₂(η-C₅Me₅)₃] is based on a triangle of metal atoms which, however, proved to be positionally disordered. The data obtained are limited, but the mean metal–metal separation is 2.56(1)Å and the two CO groups are tilted in a way which implies semi-triply bridging behaviour. The important feature that the C₅Me₅ ligand on copper is η⁵-co-ordinated is confirmed.