SYNTHESIS AND CHARACTERIZATION OF IRON(III) COMPLEXES WITH UNSYMMETRICAL QUADRIDENTATE SCHIFF BASES AND SPIN EQUILIBRIUM BEHAVIOR IN SOLUTION.

Abstract

Several iron(III) complexes with planar unsymmetrical quadridentate Schiff bases composed of 1:1:1 condensation products of acetylacetone, ethylenediamine, and each of salicylaldehyde and o-hydroxyacetophenone have been prepared and characterized, where the Schiff bases are abbreviated as (H//2salacen) and (H//2hapacen), respectively. The effective magnetic moment of left bracket FeCl(hapacen) right bracket increases gradually from 3. 46 BM at 80 K to 5. 31 BM at 301 K, and was interpreted by a spin-spin interaction model based on a binuclear structure with an antiferromagnetic interaction parameter of J equals minus 10 cm** minus **1 (S//1 equals S//2 equals 5/2), while the magnetic moment for left bracket FeCl(salacen) right bracket is 5. 86 BM at 80 K and 5. 96BM at 302 K, indicating that the complex is a monomeric species of high-spin type.