Synthesis, Characterization, and Magnetism of Binuclear Iron(III) Complexes with Iodanilato as Bridging Ligand

Abstract Three new μ‐iodanilato‐bridged binuclear iron(III) complexes were synthesized and characterized, namely [Fe2(IA)(Me2phen)4](ClO4)4 (1), [Fe2(IA)(Ph2phen)4](ClO4)4 (2), and [Fe2(IA)(Phphen)4]‐(ClO4)4 (3), where IA represents the dianion of iodanilic acid; Me2phen, Ph2phen, and Phphen denotes 2,9‐dimethyl‐1,10‐phenanthroline; 4,7‐diphenyl‐1,10‐phenanthroline or 5‐phenyl‐1,10‐phenanthroline, respectively. Based on elemental analyses, molar conductivity and room‐temperature magnetic moment measurements, IR and electronic spectral studies, it is proposed that these complexes have extended IA‐bridged structures consisting of two iron(III) ions, each in a distorted octahedral environment. The complexes (1) and (2) were further characterized by variable‐temperature (4.2–300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, Ĥ = −2JŜ 1 Ŝ 2, giving the exchange parameter J = −9.21 cm−1 for (1) and J = −10.85 cm−1 for (2). These results are commensurate with weak antiferromagnetic spin‐exchange interaction between the two iron(III) ions within each molecule. The influence of halogen substituents in the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is preliminarily discussed.