Photoinduced Catalytic Organic-Hydride Transfer to CO 2 Mediated with Ruthenium Complexes as NAD + /NADH Redox Couple Models.

The catalytic organic-hydride transfer to CO 2 was first achieved through the photoinduced two-electron reduction of the [Ru(bpy) 2 (pbn)] 2+ /[Ru(bpy) 2 (pbnHH)] 2+ (bpy=2,2'-bipyridine, pbn=2-(pyridin-2-yl)benzo[b]-1,5-naphthyridine, and pbnHH=2-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine) redox couple in the presence of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). The active species for the catalytic hydride transfer to carbon dioxide giving formate is [Ru(bpy)(bpy⋅ - )(pbnHH)] + formed by one-electron reduction of [Ru(bpy) 2 (pbnHH)] 2+ with BI⋅.