Structural Characterization of Iron(iii) Dinuclear Complexes

Abstract

Dinuclear complexes have been studied for different purposes: magnetic materials[1], Non-linear optics materials[2], molecular switches [3], mixed-valence systems, etc. With these antecedents in mind, we present in this work a new series of dinuclear Iron(III) complexes formed by different Schiff bases ligands. The reaction starting from the iron chloride salts with the 5-chloro or 5-bromosalycilaldehyde and ethylendiamine yields two different kinds of dinuclear iron complexes in different reaction conditions. The first one (Fig Nº1), are methoxo-bridged dinuclear iron(III) complexes in which each metal centre is coordinated with one monocondensated Schiff base ligand, one 4-chloro or 4-bromo-2-(dimethoxymethyl)phenoxo ligand and two bridging methoxo ligands. The iron(III) centres are hexacoordinated (FeN2O4), the coordination sphere is formed by 2 nitrogen atoms of the ethylendiamine fragment, 2 oxygen atoms from the hydroxyl of the Schiff base and two O atoms from the methoxo ligands. Both iron(III) centres are related by a inversion centre. The second one (Fig Nº2), the dinuclear complex is formed for the double condensation of ethylendiamine with 5-chloro or 5-bromo-salycilaldehyde and one oxygen from the dianionic ligand act as bridge with another unit. The iron (III) centres are also hexaccordinated (FeN2O3Cl) formed by 2 nitrogen atoms from ethylendiamine fragment and 3 oxygen atoms from hydroxyl from Schiff base ligands and one chloro ligand. Finally, the electronic and redox properties have been studied by UV-Visible and cyclic voltammetry.