Unusually Large Tunneling Effect on Highly Efficient Generation of Hydrogen and Hydrogen Isotopes in pH-Selective Decomposition of Formic Acid Catalyzed by a Heterodinuclear Iridium-Ruthenium Complex in Water

A heterodinuclear iridium-ruthenium complex [Ir(III)(Cp*)(H(2)O)(bpm)Ru(II)(bpy)(2)](SO(4))(2) {1(SO(4))(2), Cp* = eta(5)-pentamethylcyclopentadienyl, bpm = 2,2'-bipyrimidine, bpy = 2,2'-bipyridine} acts as the most effective catalyst for selective production of hydrogen from formic acid in an aqueous solution at ambient temperature among catalysts reported so far. An unusually large tunneling effect was observed for the first time for the catalytic hydrogen production in H(2)O vs D(2)O.