Mechanism of oxidative dehydrogenation of alcohols co-ordinated to ruthenium

Abstract

The oxidative dehydrogenation of the complexes [Ru(bipy)₂(NC₅H₄CH₂OH)]²⁺, [Ru(bipy)₂(NC₅H₄CD₂OH)]²⁺ and [Ru(bipy)₂{NC₅H₄CH(CH₃)OH}]2+ to the corresponding carbonyl species [bipy = 2,2'-bipyridine; NC₅H₄CH₂OH = 2-(hydroxymethyl)pyridine; NC₅H₄CD₂OH = 2-(dideuteriohydroxymethyl)pyridine; NC₅H₄CH(CH₃)OH = 2-(1-hydroxyethyl)pyridine] has been studied in aqueous solution by kinetic and electrochemical techniques. The mechanistic scheme was found to involve the intermediacy of a ruthenium(IV)–alkoxide species, formed by disproportionaton of the ruthenium(III) complex produced in the initial step of the oxidation process. The rate-determining removal of the proton from the α-carbon atom of the chelate ring is general-base catalysed.