Magnetostructural correlations in exchange coupled phenoxo-, alkoxo-, and hydroxo-bridged dinuclear iron(III) compounds

A new semi-empirical magnetostructural correlation for exchange coupled dinuclear asymmetrically phenoxo-, alkoxo-, and hydroxo-bridged iron(III) complexes has been established. Based on an extensive comparison of the magnetic and structural parameters of 34 compounds, a strong correlation bem,een the exchange coupling constant J and the averaged iron-oxygen distance, d, over the phenoxo-, alkoxo-, and hydroxo-bridge, could be demonstrated, This bridge provides much more efficient exchange pathway than every bridges over three atoms. e.g. acetate, phosphate, sulfate. The empirical relationship could be quantified in the form J = -10(-) exp(-6.8d). The magnitude of the Fe-O(X)-Fe-bridging angle has no noticeable influence on the exchange coupling neither in case of complexes with identical nor in case of such with different bridging ligands. (C) 2001 Elsevier Science B.V. All rights reserved.