Electrochemical preparation and properties of poly-cis-[{RuIII(L)2(OH2)}2O]4+ (L=pyrrole-substituted-2,2′-bipyridine) modified electrodes. Their electroinduced transformations into poly-cis-[RuII(L)2(H2O)2]2+ and poly-cis-[RuII(L)2(CH3CN)2]2+ films

The ruthenium μ-oxo bipyridyl dimer cis-[{RuIII(bpy)2(OH2)}2O]4+ (1) (bpy=2,2′-bipyridine) is a remarkable catalyst for the oxidation of water, chloride ion or organic compounds. Only rare examples of immobilization of such catalysts on electrode surfaces have been reported; all attempts are based on the incorporation of 1 into thin polymeric films. These devices are reputed to have rather poor stability due to the leaching of the complex from the film. In this article, we report the syntheses of [{RuIII(L)2(OH2)}2O]4+ complexes containing substituted bpy ligands L (L=4-(4-pyrrol-1-yl-butyl)-4′-methyl-2,2′-bipyridine (L1), complex (2) or 4,4′-di-tert-butyl-2,2′-bipyridine (L2), complex (3)) from the corresponding mononuclear aquo precursors cis-[RuII(L1)2(H2O)2]2+ (4) and cis-[RuII(L2)2(H2O)2]2+ (5). Stable functionalized polypyrrole modified electrodes containing the 2-core are obtained by anodic electropolymerization of solutions of 2 in the aprotic non-coordinating solvent CH2Cl2. Their electrochemical behavior in aqueous media at several pH values is studied. Some examples of electroinduced transformations occurring within the polymeric films leading to the tailoring of modified electrodes of poly-4 and cis-[RuII(L1)2(CH3CN)2]2+ are also reported.