Mössbauer, vibrational and electronic spectroscopy of trinuclear μ-oxo iron(III) acetate clusters with pyridine and derivatives as ligands

Abstract

In this study we have investigated eight complexes of the general composition [Fe 3O(OOCCH 3) 6(L) 3]NO 3, where L is a heterocyclic ligand, viz. a 4-substituted pyridine. The Mössbauer spectra of the complexes showed isomer shifts and quadrupole splittings that are characteristic of iron(III) high-spin complexes. The Mössbauer quadrupolar doublets showed asymmetries that are attributed principally to the Goldanskii-Karyagin effect. A correlation is proposed between the Mössbauer parameters, and between the energy of the charge transfer band spectra, and the p K a values of the N-heterocyclic ligands.