Synthesis, characterization, and catalytic oxygenation activity of dinuclear iron(III) complex supported by binaphthol-containing chiral ligand

A diiron(RI) complex supported by a new dinucleating ligand containing a chiral binaphthol spacer has been synthesized and characterized by elemental analysis and spectroscopic methods (ESI-MS, CD, and UV-vis). The complex has a (mu-oxo)(mu-carboxylato) doubly bridged diiron(M) core, the structural motif of which resembles that of the active site of sMMO and related diiron enzymes. Catalytic oxidation of alkanes with m-CPBA proceeded very efficiently to give the corresponding alcohols as the major products together with ketones as minor products. The alcohol-selectivity (alcohol/ketone = 3.8-8.8) as well as the kinetic deuterium isotope effect (k(H)/k(D) = 3.0 for the oxidation of cyclohexane) and significantly high regioselectivity (tertiary carbon/secondary carbon = 17.1) in the oxidation of adamantane strongly suggested a reaction mechanism involving a highly reactive metal-based oxidant rather than an autooxidation mechanism involving free radical species. (C) 2004 Elsevier B.V. All rights reserved.