Redox Active Cobalt NHC Catalyst for Oxidation of Alkenes to Carbonyl Compounds at Room Temperature: Water as Source of Oxygen.

A Co(III) complex is synthesized with a redox-active N-heterocyclic carbene (NHC) ligand, and the structure of this complex is established by single-crystal XRD. This bimetallic Fe^Fe^Co complex was explored in an alkene oxidation reaction to give aldehydes as products, which could be accomplished via water oxidation catalysis at room temperature. In the proposed mechanism, both metal-ligand cooperativity as well as bimetallic participation of the two metals Co and Fe (of one unit of ferrocene moiety) further facilitates the two oxidation cycles altogether. The peroxo intermediate in the catalytic water oxidation cycle is proposed to be the crucial intermediate species for the conversion of the unsaturated system into its corresponding aldehydes.