Electrosynthesis, physico-chemical and electrocatalytic properties of a novel electroactive Ru(0) material based on the (Ru(terpy)(CO)) frame (terpy=2,2′:6′,2′′-terpyridine)

The preparation of an electroactive material based on a (Ru(terpy)(CO)) frame (terpy=2,2′:6′,2′′-terpyridine) has been achieved by the two electron reduction of trans- or cis-[Ru(terpy)(CO)Cl2] complexes. During this electrochemical process, two chloride ligands are released and metalmetal bonds are formed. The highly coloured resulting compound containing RuRu bonds can either be coated as a film on an electrode surface in acetonitrile electrolyte or generated as a soluble product in DMSO electrolyte. The nature of this material does not depend on the stereochemistry of the starting complex and its characterization, either as a solid and in solution, has been investigated by an interplay between electroanalytical and spectroscopic techniques including 1H-NMR, UV–vis, MS and IR. It appears from the data that one of the possible structure of the material is an oligomeric [Ru(terpy)(CO)]n with n=3. The trans- and cis-[Ru(terpy)(CO)Cl2] complexes and the related organometallic metal–metal based material display catalytic activity in the electroreduction of carbon dioxide in hydro-organic media. Interestingly, [Ru(terpy)(CO)]n modified electrodes also display electrocatalytic activity in purely aqueous solutions.