The interaction between anionic and cationic rhodium(I) complexes in solution and in the solid state

Abstract

U.v.–visible spectral studies show that in acetonitrile solution there is association between [Rh(CO)₂(L–L)]⁺ or [Rh(CO)₃(L–L)]⁺[where L–L = 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen)] cations and [RhX₂(CO)₂]^–(where X = Cl or Br) anions. The extent of the interaction depends on L–L and X and is most pronounced for [Rh(CO)₃(phen)]⁺ and [RhCl₂(CO)₂]^–. The anion–cation compound formed by the reaction of L–L with [(OC)₂Rh(µ-Cl)₂Rh(CO)₂] has been shown to be [Rh(CO)₃(L–L)][RhCl₂(CO)₂]. All four compounds of the type [Rh(CO)₃(L–L)][RhX₂(CO)₂] have been prepared in crystalline form by the action of CO on a solution of [Rh(cod)(L–L)][BPh₄](cod = cyclo-octa-1,5-diene) and [RhX₂(CO)₂]^– in 1,2-dichlorobenzene, a new preparative method.