Photoinduced Nitrite Reduction to NO: Closing the Cycle with Dinuclear Ruthenium Complexes.

The reduction of nitrite to nitric oxide (NO) is a crucial step in the nitrogen cycle, catalyzed by nitrite reductase in nature, and its efficient catalysis is of great interest. This study reports the achievement of a reduction cycle that releases NO from nitrite using a dinuclear ruthenium complex (NO + 2H + e → NO + HO). Irradiation or thermolysis of a nitrite-bridged complex, [(TpRu)(μ-Cl)-(μ-NO)-(μ-pz)] () (Tp = HB-(pyrazol-1-yl)), resulted in the formation of an oxido-bridged complex, [(TpRu)(μ-Cl)-(μ-O)-(μ-pz)] (), and the release of NO. The reaction mechanism from to was investigated through theoretical calculations. To complete the reduction cycle, complex was reproduced from complex using two protons and one electron in the presence of a nitrite salt. This study demonstrated the successful mimicking of the function of nitrite reductase using a dinuclear ruthenium complex.