Jason A. Halfen

Reversible cleavage and formation of the dioxygen O-O bond within a dicopper complex

A key step in dioxygen evolution during photosynthesis is the oxidative generation of the O-O bond from water by a manganese cluster consisting of M2(μ-O)2 units (where M is manganese). The reverse reaction, reductive cleavage of the dioxygen O-O bond, is performed at a variety of dicopper and di-iron active sites in enzymes that catalyze important organic oxidations. Both processes can be envisioned to involve the interconversion of dimetal-dioxygen adducts, M2(O2), and isomers having M2(μ-O)2 cores. The viability of this notion has been demonstrated by the identification of an equilibrium between synthetic complexes having [Cu2(μ-η2:η2-O2)]2+ and [Cu2(μ-O)2]2+ cores through kinetic, spectroscopic, and crystallographic studies.

Catalytic reduction of nitric oxide to nitrous oxide by alcohols mediated by copper(I) complexes

In a reaction relevant to environmetally important processes carried out by copper-containing enzymes and heterogeneous catalysts, copper(I) complexes of 1,4,7-triisopropyl-1,4,7-triazacyclononane dissolved in alcohols (e.g. benzyl alcohol) efficiently promote the reduction of NO to N2O by the solvent at room temperature, yielding the respective carbonyl compounds (e.g. benzaldehyde).