ELECTROCHEMICAL PROPERTIES OF [(C5ME5)RHIII(L)CL]-BIPYRIDINE OR 1,10-PHENANTHROLINE DERIVATIVES) IN SOLUTION AND IN RELATED POLYPYRROLIC FILMS - APPLICATION TO ELECTROCATALYTIC HYDROGEN GENERATION( COMPLEXES (L=2,2')

Electrochemical characterization of a series of rhodium(III) complexes [(C5Me5)Rh(III)(L)Cl]+ containing a 2,2'-bipyridine or 1,10-phenanthr oline derivative as the ligand L is described. The reduction involves a bielectronic reduction of the metal centre leading to [(C5Me5)Rh(I)( L)Cl]- which is in equilibrium with the chloro-less species [(C5Me5)Rh (I)(L)]0. The relative amounts of the two compounds depend on the natu re of the ligand L. Films of the corresponding substituted polypyrrole s are prepared by oxidative polymerization of the complexes containing a pyrrole-ligand derivative. Immobilization of the complexes into a p olymeric film allows the build up of the reactive species [(C5Me5)Rh(I II)(L)]2+ as a consequence of its slow coordination by the released ch loro ligand into the polymeric form. The electrocatalytic ability of t hese polypyrrolic rhodium(III) complex films for hydrogen evolution ha s been demonstrated.