Mössbauer and electronic spectral characterization of homo-bimetallic Fe(III) complexes of unsymmetrical [N10] and [N12] macrocyclic ligands

The homo-bimetallic complexes of stoichiometry Fe2(L)ClO4(ClO4)2 where L are novel unsymmetrical [N10] (L1·2HClO4) and [N12] (L2·2HClO4) 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 HClO4. 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. μeff values of the complexes suggest presence of antiferromagnetically coupled (Fe3+–Fe3+ = S5/2–S5/2) 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.