MOSSBAUER, VIBRATIONAL AND ELECTRONIC SPECTROSCOPY OF TRINUCLEAR MU-OXO IRON(III) ACETATE CLUSTERS WITH PYRIDINE AND DERIVATIVES AS LIGANDS

In this study we have investigated eight complexes of the general comp osition [Fe3O(OOCCH3)(6)(L)(3)]NO3, where L is a heterocyclic ligand, viz. a 4-substituted pyridine. The Mossbauer spectra of the complexes showed isomer shifts and quadrupole splittings that are characteristic of iron(III) high-spin complexes. The Mossbauer quadrupolar doublets showed asymmetries that are attributed principally to the Goldanskii-K aryagin effect. A correlation is proposed between the Mossbauer parame ters, and between the energy of the charge transfer band spectra, and the pK(a) values of the N-heterocyclic ligands.