Complexes of iron(III) salen and saloph Schiff bases bridged by dicarboxylic acids

Six dinuclear Fe-III complexes involving tetradentate Schiff bases N,N'-bis(salicylidene)ethylenediamine (salenH(2)) or bis(salicylidene)o-phenylenediamine (salophH(2)) with 2,6-pyridinedicarboxylic acid (2,6-dicarpyH(2)), thiodiglycolic acid (tdgaH(2)) or 3,3'-thiodipropionic acid (3,3'-tdpaH(2)) have been synthesized and characterized by elemental analysis, IR spectroscopy and conductivity measurements. The magnetic behaviour of all complexes has been studied between 77-298 K. The dicarboxylic acids form bridges between paramagnetic centers and weak antiferromagnetic intramolecular exchanges were found. Thus, the complexes can be characterized as high spin distorted octahedral iron(III), except for [{Fe(saloph)}(2)(2,6-dicarpy)], where S-1 = S-2 = 3/2 spin-exchange model complies best with experimental data and the iron(III) has probably square-pyramidal coordination mode. The HDW S-1 = S-2 = 5/2 spin-exchange model with ((H) over cap = -2 (S) over cap(1)(S) over cap(2)) was applied in the case of the other complexes. The antiferromagnetic coupling parameters J vary in the range of -1.06 to -5.87 cm(-1).