Temperature dependence of photocatalytic CO reduction by trans(Cl)-Ru(bpy)(CO)Cl: activation energy difference between CO and formate production.

The temperature dependence of photocatalytic CO reduction by trans(Cl)-Ru(bpy)(CO)Cl (bpy: 2,2'-bipyridine) has been researched in ethanol (EtOH)/N,N-dimethylacetamide (DMA) solutions containing [Ru(bpy)] (a photosensitizer) and 1-benzyl-1,4-dihydronicotinamide (BNAH, an electron donor). The catalytic system efficiently reduces CO to carbon monoxide (CO) with formate (HCOO) as a minor product. The mechanism of the catalysis consists of the electron-relay cycle and the catalytic cycle: in the former cycle the photochemically generated reduced species of the photosensitizer injects an electron to the catalyst, and in the latter the catalyst reduces CO.