Ruthenium(II) Complexes of a Xanthene-Spanned Dicarbene Ligand.

Octahedral ruthenium(II) complexes of a xanthene-di(-heterocyclic carbene) ancillary ligand (XdC) have been prepared and structurally characterized. Examples catalyze the transfer hydrogenation of ketones {[Ru(CO)I(,,'-XdC)] () and [Ru(CO)(MeCN)(,,'-XdC)] ()} and the selective electrochemical reduction of CO to CO {[Ru(,'-bpy)(CO)(,,'-XdC)] () at 0.40 V overpotential in MeCN-HO (1 M)}.