Binuclear Binuclear complexes of rhodium or copper with pentamethylcyclopentadienyltricarbonyltungsten. Crystal structure of (η⁵-C₅Me₅)(CO)W(μ-CO)₂Rh(PPh₃)₂

The reaction of Li[W(CO)₃Cp^{{black star}}] (Cp^{p{black star}} = ?⁵-C₅Me₅) with [RhCl(PPh₃)₃] affords [Cp^{{black star}}(CO)W(µ-CO)₂Rh(PPh₃)₂],3, which has been structurally characterised by an X-ray diffraction study, and shown to contain a short WRh bond of 2.5820(6) Å and two semi-bridging CO ligands. Variable temperature ³¹P{¹H} NMR spectra show that complex 3 is fluxional in solution and undergoes intramolecular interchange of inequivalent PPh₃ with ?G‡ca. 30 kJ mol^-1 at -105°C. Reaction of Li[W(CO)₃Cp^{{black star}}] with [RhCl(PPh₃)₃] gives the mono-triphenylphosphine complex [Cp^{{black star}}W(CO)₃Cu(PPh₃)], 4a, which has the same valence electron count as 3 and has been characterised analytically and by IR and NMR spectroscopy. Evidence for a related molybdenum-copper species, 4b, is also presented. The structural and spectroscopic properties of new products are discussed in relation to those of related heterobinuclear compounds. © 1995.