Some aspects of the reactivity of rhodium(I) and rhodium(II) tricyclohexylphosphine derivatives studied by ESR spectroscopy II. Formation of a paramagnetic Rh(II) carbonyl species by treatment of RhCl2(PCy3)2 in the solid state with carbon monoxide

The behaviour of RhCl(PCy 3 ) 2 in the solid state towards O 2 , Co, and H 2 was investigated. Whereas no reaction occurred with dioxygen and dihydrogen, treatment with carbon monoxide led to the formation of RhCl 2 (CO)(PCy 3 ) 2 , which is the first example of a paramagnetic carbonyl Rh(II) derivative. The product is rather labile but the life-time in the solid state was long enough to allow the spectroscopic study of the decay process. ESR and IR spectra indicated a disproportionation reaction to Rh(I) and Rh(II) carbonyl species.