Some silyl and germyl compounds of six-co-ordinated rhodium(III) carbonyl halides

Abstract

Reaction between trans-[Rh(CO)Cl(PEt3)2](1) and MH3Cl (M = Si or Ge) at low temperatures gives equimoler adducts characterised by 1H and 31P n.m.r. spectra as [RhH(CO)Cl(PEt3)2(MH2Cl)] with mutually trans phosphine ligands and M trans to H. Similar reactions occur between trans-[Rh(CO)I(PEt3)2](2) and MH3I. Some of the adducts have been isolated by evaporating solvent at low temperature. Both (1) and (2) give similar adducts with MH4, MH3Me, SiH3CH2CHCH2, and SiH2MeX (X = Cl or I); these dissociate reversibly between 200 K and 280 K, and thermodynamic parameters for dissociation of some of them have been determined from the n.m.r. spectra. Dissociation of the adducts of (2) with organosilanes and with methylgermane is fast on the n.m.r. time-scale, whereas dissociation of the adducts of (1) is slow. The reaction between (1) and MH3I gives adducts with Cl bound to M and I bound to Rh as the thermodynamically stable products; no halogen exchange was observed in the reaction between (2) and MH3Cl.