The thermodynamic propensity of a metal hydride complex to transfer a hydride to a substrate varies considerably between solvents. Water-soluble, bis-phosphine complexes of nickel hydrides were studied to determine the relative hydricities in acetonitrile and aqueous solution. In acetonitrile, formate is a better hydride donor than [HNi(dmpe)2]+ by 7 kcal/mol, and no hydride transfer from [HNi(dmpe)2]+ to CO¬2 occurs. The hydride donating ability of [HNi(dmpe)2]+ is greatly improved in water relative to acetonitrile, in that reduction of CO2 to formate by [HNi(dmpe)2]+ was found to be thermodynamically downhill by 8 kcal/mol.
Published: February 3, 2022
Citation
Connelly S.J., C.M. Zall, D.L. Miller, J.C. Linehan, and A.M. Appel. 2016.Solvent Influence on the Thermodynamics for Hydride Transfer from Bis(diphosphine) Complexes of Nickel.Dalton Transactions 45, no. 24:10017-10023.PNNL-SA-111204.doi:10.1039/C6DT00309E