A nickel pyridine-selenolate complex for the photocatalytic evolution of hydrogen from aqueous solutions

A nickel pyridine-selenolate complex, [Ni(4,4'-dmbpy)(2-pySe)(2)] (1, where 4,4'-dmbpy = 4,4'-dimethyl-2,2'-bipyridine, and 2-pySe = pyridine-2-selenolate), has been synthesized, and investigated for photocatalytic production of H-2 from aqueous solution. Electrochemical studies show that the nickel complex 1 can efficiently electrocatalyze Hy evolution from weakly acidic solutions. Under visible-light irradiation (lambda > 420 nm), the complex 1 displays impressive H-2 evolution activity with a TON of 1340 (based on a catalyst) in a noble-metal-free system, which contains fluorescein (Fl) as photosensitizer and triethylamine (TEA) as sacrificial electron donor in acetonitrile-water solution. It should be noted that complex 1 is the rare example of nickel pyridineselenolate complex as molecular photocatalyst for water reduction.