Synthesis, characterization and catalase-like activity of the tetranuclear iron(III) complex involving a (μ-oxo)(μ-hydroxo)bis(μ-alkoxo)tetra(μ-carboxylato)tetrairon core

Abstract

The synthesis, characterization and catalase-like activity of the tetranuclear complex [Fe4(μ-O)(μ-OH)(μ-OAc)4(L)2](ClO4)3 (HL is the ligand 1,3-bis[(2-aminoethyl)amino]-2-propanol) is described herein. The complex was obtained from the self-assembly of Fe(ClO4)3·xH2O, NaOAc·3H2O and HL. The X-ray structural elucidation, together with spectroscopic and ESI-MS data, disclosed a (μ-oxo)(μ-hydroxo)bis(μ-alkoxo)tetra(μ-carboxylato)tetrairon core structure that can be described as a dimer of dimer, where the four metallic centers are embedded in the same chemical environment. The kinetics of the catalase-like activity was investigated in water, TRIS buffer and acetonitrile, and it revealed a Michaelis–Menten behavior. The progress of H2O2 disproportionation reactions was followed by UV–Vis, ESI-MS/Q-TOF and EPR, indicating the disruption of the tetranuclear core, which was accelerated at higher proton concentration. The rate constant was higher in CH3CN than in aqueous solution (kobs(CH3CN)>kobs(buffer)>kobs(H2O)).