title: Experimental and theoretical examination of C-CN and C-H bond activations of acetonitrile using zerovalent nickel.
abstract: Experimental and density functional theory show that the reaction of acetonitrile with a zerovalent nickel bis(dialkylphosphino)ethane fragment (alkyl = methyl, isopropyl) proceeds via initial exothermic formation of an eta(2)-nitrile complex. Three well-defined transition states have been found on the potential energy surface between the eta(2)-nitrile complex and the activation products. The lowest energy transition state is an eta(3)-acetonitrile complex, which connects the eta(2)-nitrile to a higher energy eta(3)-acetonitrile intermediate with an agostic C-H bond, while the other two lead to cleavage of either the C-H or the C-CN bonds. Gas-phase calculations show C-CN bond activation to be endothermic, which contradicts the observation of thermal C-CN activation in THF. Therefore, the effect of solvent was taken into consideration by using the polarizable continuum model (PCM), whereupon the activation of the C-CN bond was found to be exothermic. Furthermore the C-CN bond activation was found to be favored exclusively over C-H bond activation due to the strong thermodynamic driving force and slightly lower kinetic barrier.
authors.affiliation: Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Tülay A
authors.initials: TA
authors.lastname: Ateşin
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lachaize
authors.forename: William W
authors.initials: WW
authors.lastname: Brennessel
authors.forename: Juventino J
authors.initials: JJ
authors.lastname: García
authors.forename: William D
authors.initials: WD
authors.lastname: Jones