Kinetics of the oxidation of benzyl alcohol by tris(2,2′-bipyridine)nickel(III) ions in aqueous perchlorate media

Abstract

The oxidation of benzyl alcohol by [Ni(bipy)₃]³⁺ is first-order in both Ni^III and the alcohol. The observed independence of the second-order rate constant with acidity conforms with the following previous findings: (a)[Ni(bipy)₃]³⁺ oxidizes substrates in the outer sphere without removal of a 2,2′-bipyridine from Ni^III; (b) equilibrium studies on solvent-sorting in the solvation of the proton predict that the tendency for benzyl alcohol (BzOH) to form an oxidatively inactive {H⁺(H₂O)_x–1 ROH} complex from ROH and {H⁺(H₂O)_x} should be low. The transition-state parameters are compared for several substrates oxidized by [Ni(bipy)₃]³⁺.