Reactions of phosphine with carbonylbis(triethylphosphine)-rhodium(I) halides and derivatives

The complex trans-[Rh(CO)X(PEt3)2]1(X = Cl, Br, I or NCS) reacts with PH3 in dichloromethane at 183 K to give [Rh(CO)(PH3)2(PEt3)2]+2 which in turn reacts with CO in dichloromethane at 213 K to give [Rh(CO)2(PH3)(PEt3)2]+. The complex [Rh(CO)Cl2H(PEt3)2], formed by reaction of 1 and HCl, reacts with PH3 in dichloromethane at 219 K to give [Rh(CO)Cl(H)(PH3)(PEt3)2]+; on warming, further displacement reactions with PH3 give first [RhCl(H)(PH3)2(PEt3)2]+ and then the tris(phosphine) species [RhH(PH3)3(PEt3)2]2+. Enrichment with 13C in the carbonyl positions enabled the use of 13C NMR spectroscopy to investigate these reactions and the parameters of eleven rhodium complexes observed in this work are given.