A combined experimental and computational study of the magnetic superexchange within a triangular (μ3-O)-pyrazolato-Fe III3 complex

Abstract

The triangular complex [FeIII3(μ3-O) (μ-4-O2N-C3H2N2) 6Br3]2- has been characterized and studied by magnetic susceptibility measurements, 57Fe Mössbauer and electron paramagnetic resonance (EPR) spectroscopic methods. A combination of experimental and computational results has allowed the differentiation between two sets of acceptable isotropic exchange constants. The magnetic exchange within this complex has been modelled by a spin Hamiltonian involving antiferromagnetic exchange constants of average value Jav = -81.4 cm-1 and an antisymmetric exchange |dz| = 1.40 cm -1. Pyrazolato bridges have both a structural role and a non-negligible participation in magnetic exchange in trinuclear oxido-iron complexes Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.