Thermodynamic properties of the Ni-H bond in complexes of the type [HNi(P2RN2R')2](BF4) and evaluation of factors that control catalytic activity for hydrogen oxidation/production

Thermodynamic data for hydride complexes of the general formula [HNi((P2N2R')-N-R)(2)](BF4), 3, which have been reported previously to function as effective catalysts for the electrochemical oxidation or production of hydrogen, have been determined. Values of Delta G degrees(H+), Delta G degrees(H center dot), and Delta G degrees(H-) have been determined for 3a where R = Cy, R' = Bz, for 3b where R = R' = Ph, and for the new complex 3c, R = Ph, R' = Bz. In addition, the Delta G values for the heterolytic addition of hydrogen to the Ni(II) precursor complexes [Ni((P2N2R')-N-R)(2)](BF4)(2), 1a-c, have been determined experimentally or calculated. The data are useful for understanding the factors that control the catalytic activities observed for these complexes and for the design of additional catalysts.