Proton Knight shifts and antiferromagnetic exchange in dimeric oxygenbridged Schiff-base–iron(III) complexes

Abstract

N.m.r. data are reported for oxygen-bridged iron(III) complexes of the type (Fe^IIIL₂)₂O where L is a bidentate Schiff-base ligand. The temperature-dependence of the proton Knight shifts in the ligands has been interpreted in terms of the contact hyperfine interaction constant A and exchange integral J. The fitting of these shifts represents a novel method for the evaluation of J in such systems.