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-p henylenediamine (salophH(2)) with 2,6-pyridinedicarboxylic acid (2,6-d icarpyH(2)), thiodiglycolic acid (tdgaH(2)) or 3,3'-thiodipropionic ac id (3,3'-tdpaH(2)) have been synthesized and characterized by elementa l analysis, IR spectroscopy and conductivity measurements. The magneti c behaviour of all complexes has been studied between 77-298 K. The di carboxylic acids form bridges between paramagnetic centers and weak an tiferromagnetic intramolecular exchanges were found. Thus, the complex es can be characterized as high spin distorted octahedral iron(III), e xcept for [{Fe(saloph)}(2)(2,6-dicarpy)], where S-1 = S-2 = 3/2 spin-e xchange model complies best with experimental data and the iron(III) h as 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 antiferrom agnetic coupling parameters J vary in the range of -1.06 to -5.87 cm(- 1).