A Dinuclear Ni(0) Complex That Catalyzes Electron Transfer from H2 to Substrates

Model studies have been conducted to mimic the function of enzymes called [NiFe] and [FeFe] hydrogenases, which generate electrons via a hydride ion through the heterolytic activation of H2. Although several syntheses of hydride species or low-valent species of Ni or Fe complexes from H2 have been reported, the synthesis of dinuclear Ni(0) complexes from H2 has not been reported. Here, we report on such a dinuclear Ni(0) complex, synthesized from a mononuclear Ni(II) complex and H2. The structures of the mononuclear and dinuclear complexes were determined by X-ray analysis. Catalytic reduction of ethyl viologen or decamethylferrocenium ions as substrates using the Ni complexes and H2 was demonstrated. DFT calculations revealed that the acetate ion, added as a Lewis base, efficiently promotes the heterolytic cleavage of H2, thereby facilitating the formation of the Ni(0) complex.