Transition-metal dithiolene complexes. Part XII. Rhodium and iridium complexes

Abstract

Both [Rh{S₂C₂(CN)₂}_n^n–(n 1) and [Rh{S₂C₂(CN)₂}₃]^2– have been isolated from the reaction of Rh₂(OAc)₄ and NaS(CN)C:C(CN)SNa. the cis-dicarbonyls [Rh(CO)₂S₂C₂(CN)₂]^–, [Rh(CO)₂S₂C:C(CN)]^–₂ and [Rh(CO)₂(S₂C₆H₃Me)]^– were prepared by treatment of Rh₂(CO)₄Cl₂ with the appropriate dithiolate dianion, and evidence for the existence of [Rh(CO)₂(S₂C₆Cl₄)]^– is presented. [Rh(CO)₂S₂C₂(CN)₂]^– undergoes substitution reactions with triphenylphosphine, triethyl phosphite, and bis(trifluoromethyl)dithieten, S₂C₂(CF₃)′, giving [Rh(CO)(PPh₃)S₂C₂(CN)₂]^–, [Rh{P(OPh)₃}₂S₂C₂(CN)₂]^–, and [RhS₄C₄(CN)(CF₃)₂]_n^n–(n 1), respectively. The reactions of [Rh(CO)(PPh₃)S₂C₂(CN)₂]^– with iodine, mercury(II) chloride, mercury(II) cyanide, tetracyanoethylene, and sulphur dioxide are briefly described. Treatment of M(CO)(PPh₃)₂Cl (M = Rh or Ir) with S₂C₂(CF₃)₂ affords M₂(PPh₃)₂{S₂C₂(CF₃)₂}₃ in addition to some apparently trinuclear species. Reaction of Rh₂(CO)₄Cl₂ with S₂C₂(CF₃)₂ appears to give [Rh(CO)S₂C₂(CF₃)₂]₃^–. Many of the compounds have been examined voltammetrically, and some undergo electron transfer reactions.