High activity for oxidation reaction by peroxide adduct of binuclear iron(III) compound with ( μ- η1 : η1)-coordination mode

Abstract

Reactivities of the peroxide adducts of the iron(III) compounds with binucleating ligands, Fe 2(HPTP)(OH)(NO 3) 2 2+, Fe 2(HPTB)(OH)(NO 3) 2 2+ and Fe 2(HXTA)(CH 3COO) 2 −, were compared in the reaction with hydrogen peroxide (catalase-like function) and in the oxidation reactions of phenols and 2′-deoxyribose, (where H(HPTP), H(HPTB) and H 5(HXTA) denote N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,3-diamino-propane-2-ol, N,N,N′,N′-tetrakis(2-benzimidazolylmethyl)-1,3-diamino-propane-2-ol and N,N′-2-hydroxy-5-methyl-1,3-xylylenebis[ N-(carboxymethyl)]glycine, respectively). The peroxide adduct of the H(HPTP) complex exhibited the highest activity in all the reactions described above and the origin of the results are discussed in terms of the electrophilic nature of the peroxide adduct, electronic structure of the reactant, Lewis acidity of an iron(III) ion, orbital correlationship between metal peroxide adduct and the substrate and the steric hindrance of the ligand system. Based on these facts, we have proposed a new scheme for the catalase-like function catalysed by a binuclear iron(III) complex.