Syntheses and magnetic properties of iron(III) complexes with imidazole groups |
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Authors: | S. Okamura Y. Maeda |
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Affiliation: | (1) Department of Chemistry, Faculty of Science, Kyushu University, Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan;(2) Department of Chemistry, Faculty of Science, Kyushu University Graduate School of Sciences, Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan |
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Abstract: | Iron(III) complexes with the general formula of [Fe (R-Himap)2]X and [Fe(R-Himat)2]X (Himap = shiff-base prepared from the condensation of 4-formylimidazole and 2-aminophenol, Himat = shiff base prepared from the condensation of 4-formylimidazole and 2-aminobenzenethiol, and R = H, Me, Ph; X = ClO4, NO3, BPh4) have been synthesized. The complexes have an N4O2 donor set or an N4S2 donor set. These complexes have 5 and 5 member rings around an iron(III) atom per one chelate ring, that is, "5-5 member rings". The crystal structure, Mössbauer spectra, magnetic properties and absorption spectra of the complexes were examined. In addition, [Fe (Himsa)2]ClO4 having "5-6 member rings" of an N4O2 donor set and [Fe (Ph-Himap)(Ph-imap)] obtained by the deprotonation of [Fe (Ph-Himap)2]ClO4 have been also synthesized, and the Mössbauer spectra and magnetic properties of those complexes were examined. The X-ray structure of a single crystal of [Fe (Himap)2]BPh4 was determined: C44H36N6BO2Fe, triclinic, space group P(# 2), a = 12.452(2) Å, b = 12.748(2) Å, c = 11.996(2) Å, = 103.97(1)°, = 90.78(1)°, = 84.70(1)° and Z = 2. The moiety of an iron atom of [Fe(Himap)2]BPh4 was a pseudo octahedron with an FeN4O2 geometry. [Fe(R-Himap)2]X was in high-spin state (about 5.9 B.M. at 80 K in solid state), and [Fe(R-Himat)2]X was in low-spin state (about 2.0 B.M. at 293 K). The complex [Fe(Himsa)2]ClO4 with "5-6 member rings" and the deprotonated complex [Fe(Ph-Himap)(Ph-imap)] were in the high-spin state (6.0 B.M. at 80 K). It is concluded that the ligand field strength of an N4S2 donor set is stronger than that of an N4O2 donor set. |
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