title: Comprehensive thermodynamic characterization of the metal-hydrogen bond in a series of cobalt-hydride complexes.
abstract: A detailed structural and thermodynamic study of a series of cobalt-hydride complexes is reported. This includes structural studies of [H(2)Co(dppe)(2)](+), HCo(dppe)(2), [HCo(dppe)(2)(CH(3)CN)](+), and [Co(dppe)(2)(CH(3)CN)](2+), where dppe = bis(diphenylphosphino)ethane. Equilibrium measurements are reported for one hydride- and two proton-transfer reactions. These measurements and the determinations of various electrochemical potentials were used to determine 11 of 12 possible homolytic and heterolytic solution Co-H bond dissociation free energies of [H(2)Co(dppe)(2)](+) and its monohydride derivatives. These values provide a useful framework for understanding observed and potential reactions of these complexes. These reactions include the disproportionation of [HCo(dppe)(2)](+) to form [Co(dppe)(2)](+) and [H(2)Co(dppe)(2)](+), the reaction of [Co(dppe)(2)](+) with H(2), the protonation and deprotonation reactions of the various hydride species, and the relative ability of the hydride complexes to act as hydride donors.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ciancanelli
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Noll
authors.forename: Daniel L
authors.initials: DL
authors.lastname: DuBois
authors.forename: M Rakowski
authors.initials: MR
authors.lastname: DuBois