Redox properties of two new ruthenium(III) isocyanide complexes, trans-[NBu4][RuX4(CNTM)2](X=Cl or Br, CNTM=p-tolylsulfonylmethylisocyanide)

New ruthenium(III) complexes trans-[NBu4][RuX4(CNTM)2] (X=Cl or Br, CNTM=p-tolylsulfonylmethylisocyanide) have been prepared by treating [NBu4]2[RuX6] with the isocyanide ligand CNTM in EtOH–CH2Cl2 solution. In situ IR and UV–Vis spectroelectrochemical studies have shown that reduction of trans-[RuX4(CNTM)2]− in acetonitrile and subsequent oxidation yields mer,trans-[RuX3(CNTM)2(NCMe)]. Similar studies have shown, interestingly, that oxidation of trans-[RuX4(CNTM)2]− and subsequent reduction also yields the same product. Differences between the redox behaviour of trans-[RuX4(CNTM)2]− and trans-[RuX4(CNtBu)2]− (X=Cl or Br, CNtBu=tert-butylisocyanide) in the presence of free isocyanide ligand have also been identified.