Mechanism of Oxidative Dehydrogenation of an Amine Coordinated to Osmium(II)

Abstract

The synthesis and characterization of [Os( bpy )₂( ampy )]²⁺{ bpy = 2,2′-bipyridine; ampy = 2-( aminomethyl )pyridine} have been studied, together with its irreversible two-electron oxidative dehydrogenation to the corresponding osmium(II) imine species in aqueous solution, by utilizing electrochemical and stopped-flow kinetic techniques. The kinetic data were analysed by using numerical integration methods to obtain solutions for the differential equations derived from mechanistic proposals. The results were consistent with the initial oxidation of the metal centre to Os^III and the intermediacy of a deprotonated Os^IV species, formed by disproportionation, in the subsequent ligand dehydrogenation.