Group IVB complexes of rhodium

Abstract

A series of neutral and anionic rhodium–germanium bonded compounds have been obtained by oxidative addition reactions, e.g. [(Ph₃E)₃RhCl + R₃GeH →(Ph₃E)₂Rh(H)Cl(GeR₃), E = P or As; R = Me, Et, or Cl]. Tributylstannane reacts similarly, but Me₃SnH is decomposed to hydrogen and Me₆Sn₂. The Rh^III products dissociate extensively in solution but are mostly air stable as solids. The complex (Ph₃P)₂Rh(H)Cl(GeEt₃) loses Et₃GeH on reaction with carbon monoxide or ethylene; with hydrogen chloride triethylchlorogermane is formed. Excess of HGeCl₃ and (Ph₃P)₃RhCl give the phosphonium salt, [Ph₃PH]₃[Rh(GeCl₃)₆], and similar salts are formed by the reaction between HGeCl₃ and RhCl₃ in acid solution, e.g. [Me₃NH]₃[RhCl₃(GeCl₃)₃]. Rhodium(I)–germanium complexes, (Ph₃P)₂(CO)Rh(GeCl₃), (Ph₃P)₂(CO)₂Rh(GeEt₃), and [Rh(CO)Cl(GeCl₃)₂]^2– have been isolated. Trichlorosilane and [(C₈H₁₂)RhCl]₂ yield (C₈H₁₂)RhCl(SiCl₃)₂ whereas with (π-C₅H₅)Rh(C₈H₁₂) a cyclo-octene derivative, (π-C₅H₅)(C₈H₁₄) Rh(SiCl₃)₂ is formed.