Binuclear Binuclear complexes of rhodium or copper with pentamethylcyclopentadienyltricarbonyltungsten. Crystal structure of ( η5−C 5Me5)(CO)W(μ-CO) 2Rh(PPh 3) 2

Abstract

The reaction of Li[W(CO) 3Cp ★] (Cp p★ = η 5−C 5Me 5) with [RhCl(PPh 3) 3] affords [Cp ★(CO)W(μ-CO) 2Rh(PPh 3) 2], 3, which has been structurally characterised by an X-ray diffraction study, and shown to contain a short WRh 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 PPh 3 with ΔG‡ca. 30 kJ mol −1 at −105°C. Reaction of Li[W(CO) 3Cp ★] with [RhCl(PPh 3) 3] gives the mono-triphenylphosphine complex [Cp ★W(CO) 3Cu(PPh 3)], 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.