Nitrite Reduction Cycle on a Dinuclear Ruthenium Complex Producing Ammonia

摘要

The fundamental biogeochemical cycle of nitrogen includes cytochrome c nitrite reductase, which catalyzes the reduction of nitrite ions to ammonium with eight protons and six electrons (NO_(2)~(–) + 8H~(+) + 6 e ~(–) → NH_(4)~(+) + 2H_(2)O). This reaction has motivated researchers to explore the reduction of nitrite. Although a number of electrochemical reductions of NO_(2)~(–) have been reported, the synthetic nitrite reduction reaction remains limited. To the best of our knowledge, formation of ammonia has not been reported. We report a three-step nitrite reduction cycle on a dinuclear ruthenium platform {(TpRu)_(2)(μ-pz)} (Tp = HB(pyrazol-1-yl)_(3)), producing ammonia. The cycle comprises conversion of a nitrito ligand to a NO ligand using 2H~(+) and e ~(–), subsequent reduction of the NO ligand to a nitrido and a H_(2)O ligand by consumption of 2H~(+) and 5 e ~(–), and recovery of the parent nitrito ligand. Moreover, release of ammonia was detected.