Four-Electron Reduction of a New Ruthenium Dicarbonyl Complex Having Two NAD Model Ligands through Decarboxylation in Water.

Three Ru-CO complexes, [Ru(pbn)2(CO)2]2+, [Ru(pbn)2(CO)(COOH)]+, [Ru(pbn)2(CO)(COO)]0 [pbn = 2-(pyridin-2-yl)benzo[b]-1,5-naphthyridine], exist as equilibrium mixtures in aqueous solutions. Thermal decarboxylation of [Ru(pbn)2(CO)(COOH)]+ and/or [Ru(pbn)2(CO)(COO)]0 induces a two-electron reduction of pbn to form [Ru(pbn)(pbnHH)(CO)(OH2)]2+ [pbnHH = 2-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine] in H2O.