Reactions involving transition metals. Part IX. The structure and isomerism of some dihalogenohydridotris(ligand)rhodium(III) complexes

Abstract

The isomers α- and β-[L₃RhHX₂](L = tertiary phosphine or arsine. X = Cl or Br) are shown to have the same structures as the corresponding iridium complexes, i.e. a mer-configuration for the neutral ligands and hydride trans to halogen (α-form) or to the neutral ligand (β-form). The isomerisation β→α is enhanced by heat and light, but is inhibited in the presence of the free neutral ligand. indicating a dissociative mechanism. The bulky ligands Ph_n(C₆H₁₁)_3–nP (n= O–3) and Ph₃As give products of variable stoicheiometry but only two neutral ligands appear to be co-ordinated to the metal.