Mössbauer and electronic spectral characterization of homo-bimetallic Fe(III) complexes of unsymmetrical [N 10] and [N 12] macrocyclic ligands

Abstract

The homo-bimetallic complexes of stoichiometry Fe 2(L)ClO 4(ClO 4) 2 where L are novel unsymmetrical [N 10] (L 1·2HClO 4) and [N 12] (L 2·2HClO 4) macrocyclic ligands, have been prepared. The ligands were obtained from an in situ capping reaction of the reactive substrate, N, N′-bis( N-ethylaniline)hydrazine-1,2-diimine with a mixture of aniline or 1,3-diaminopropane and HCHO in presence of HClO 4. The compounds have been characterized by elemental analyses, conductometric, IR, FAB-mass and electronic spectral studies. IR data of complexes suggest coordination from unsymmetrical aza sites as a tridentate (N,N,N) or tetradentate (N,N,N,N) ligand. μ eff values of the complexes suggest presence of antiferromagnetically coupled (Fe 3+–Fe 3+ = S 5/2–S 5/2) spin exchange. Mössbauer parameters of the complexes support (±3/2) → (±1/2) nuclear transition in high-spin configurations of Fe(III) nuclei of the homo-bimetallic complexes with the presence of Kramer's double degeneracy.