Electrosynthesis of Electroactive Metal-Metal Bonded Polymers [Ru(CO)2L]n (L = 2,2'-Bipyridine Derivatives), Their Characterization and Catalytic Activity. A Review

This paper presents an account on the preparation, characterization and properties of conductive polymers [Ru(CO)2L]n (L = 2,2'-bipyridine derivatives). These strongly adherent and highly colored films containing Ru chains are unique examples of a new generation of organometallic polymers that possess interesting catalytic properties. The formation of these materials from mononuclear complexes like [RuCl2(CO)2L] and their properties were investigated by combined electrochemical techniques and UV-VIS, NMR, FTIR and EPR spectroscopies. The polymer is produced by electrochemically induced propagation involving the intermediate formation of dimers, tetramers and higher oligomers. The air sensitivity of this kind of Ru(0) polymers can be overcome by using polypyrrole matrix with L-attached mononuclear [RuCl2(CO)2L] precursor complexes. A following cathodic step leads, within the polypyrrole film, to the intended second polymer with Ru-Ru bonds. The morphology of this unusual hybrid polymer, investigated by scanning electron microscopy, revealed a uniform material. Regular films are formed by electrodeposition on carbon fibers. Most of these polymers possess high and selective catalytic activity in the electroreduction of carbon dioxide in aqueous media. A review with 36 references.