Thermodynamic Properties of the Ni−H Bond in Complexes of the Type [HNi(P₂^RN₂^R^‘)₂](BF₄) and Evaluation of Factors That Control Catalytic Activity for Hydrogen Oxidation/Production

Abstract

Thermodynamic data for hydride complexes of the general formula [HNi(P 2 R N 2 R ‘ ) 2 ](BF 4 ), 3, which have been reported previously to function as effective catalysts for the electrochemical oxidation or production of hydrogen, have been determined. Values of Δ G ° H+, Δ G ° H •, and Δ G ° 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 Δ G values for the heterolytic addition of hydrogen to the Ni(II) precursor complexes [Ni(P 2 R N 2 R ‘ ) 2 ](BF 4 ) 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.