Hydricities of BzNADH, CH5Mo(PMe3)(CO)2H, and C5Me5Mo(PMe3)(CO)2H in acetonitrile.

The thermodynamic hydride donor abilities of 1-benzyl-1,4-dihydronicotinamide (BzNADH, 59 +/- 2 kcal/mol), C(5)H(5)Mo(PMe(3))(CO)(2)H (55 +/- 3 kcal/mol), and C(5)Me(5)Mo(PMe(3))(CO)(2)H (58 +/- 2 kcal/mol) have been measured in acetonitrile by calorimetric and/or equilibrium methods. The hydride donor abilities of BzNADH and C(5)H(5)Mo(PMe(3))(CO)(2)H differ by 13 and 24 kcal/mol, respectively, from those reported previously for these compounds in acetonitrile. These results require significant revisions of the hydricities reported for related NADH analogues and metal hydrides.

Thermodynamic hydride donor abilities of [HW(CO)4L]- complexes (L = PPh3, P(OMe)3, CO) and their reactions with [C5Me5Re(PMe3)(NO)(CO)]+.

The thermodynamic hydride donor abilities of [HW(CO)(5)](-) (40 kcal/mol), [HW(CO)(4)P(OMe(3))](-) (37 kcal/mol), and [HW(CO)(4)(PPh(3))](-) (36 kcal/mol) have been measured in acetonitrile by either equilibrium or calorimetric methods. The hydride donor abilities of these complexes are compared with other complexes for which similar thermodynamic measurements have been made. [HW(CO)(5)](-), [HW(CO)(4)P(OMe(3))](-), and [HW(CO)(4)(PPh(3))](-) all react rapidly with [CpRe(PMe(3))(NO)(CO)](+) to form dinuclear intermediates with bridging formyl ligands.

[Ni(Et2PCH2NMeCH2PEt2)2]2+ as a functional model for hydrogenases.

The reaction of Et(2)PCH(2)N(Me)CH(2)PEt(2) (PNP) with [Ni(CH(3)CN)(6)](BF(4))(2) results in the formation of [Ni(PNP)(2)](BF(4))(2), which possesses both hydride- and proton-acceptor sites. This complex is an electrocatalyst for the oxidation of hydrogen to protons, and stoichiometric reaction with hydrogen forms [HNi(PNP)(PNHP)](BF(4))(2), in which a hydride ligand is bound to Ni and a proton is bound to a pendant N atom of one PNP ligand. The free energy associated with this reaction has been calculated to be -5 kcal/mol using a thermodynamic cycle.

Hydride donor abilities and bond dissociation free energies of transition metal formyl complexes.

The hydride complex [Pt(dmpe)2H]+ (dmpe = 1,2-bis(dimethylphosphino)ethane) reversibly transfers H- to the rhenium carbonyl complex [CpRe(PMe3)(NO)(CO)]+, giving the formyl CpRe(PMe3)(NO)(CHO). From the equilibrium constant for the hydride transfer (16.2), the DeltaGdegrees for the reaction was determined (-1.

Measurement of the hydride donor abilities of [HM(diphosphine)2]+ complexes (M = Ni, Pt) by heterolytic activation of hydrogen.

[M(diphosphine)2]2+ complexes (where M = Ni and Pt) react with hydrogen in the presence of bases to form the corresponding hydrides, [HM(diphosphine)2]+. In seven cases, equilibria have been observed from which the hydride donor ability (DeltaGdegrees(H-)) of the hydrides can be calculated. For six of these complexes, the DeltaGdegrees(H-) values calculated using heterolytic activation of hydrogen are compared with those based on thermodynamic cycles using pK(a) measurements and electrochemical half-wave potentials.