ELECTRONIC AND SPATIAL STRUCTURE OF SPIN TRANSITION IRON(II) TRIS(4-AMINO-1,2,4-TRIAZOLE) NITRATE AND PERCHLORATE COMPLEXES

Electronic and spatial structure of polynuclear iron(II) complexes Fe(ATr)(3)(ClO4)(2), Fe(ATr)(3)(NO3)(2), and Fe0.34Zn0.66(ATr)(3)(NO3)(2) (where ATr is 4-amino-1,2,4-triazole) is investigated using EXAFS and XANES spectroscopy and X-ray fluorescent spectroscopy. Changes in the distances to the first four coordination spheres of Fe and Zn atoms upon spin transitions induced by variations of the anion or temperature are analyzed. It is shown that in polynuclear complexes the spin transition (from S = 2 to S = 0) is accompanied by pronounced variations in the electronic and spatial structure. A mutual effect of Fe and Zn atoms was found which alters the local environment of the low-spin Fe atoms in a magnetically diluted complex as compared to the initial one.