Spin crossover in a supramolecular FeII-FeIII system

Hiromi Ohta, Yukinari Sunatsuki, Yuichi Ikuta, Naohide Matsumoto, Seiichiro Iijima, Haruo Akashi, Takashi Kambe, Masaaki Kojevia

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Abstract

The structure of [FeII(H3L)](ClO4)2·3H 2O, where H3L is a tripodal hexadentate ligand derived from the 1:3 condensation of tris(2-aminoethyl)amine and 4-formylimidazole, has been determined by X-ray crystallography at 113 and 293 K. A spin transition was inferred from the Fe-N bond distances. The temperature dependence of the magnetic susceptibility revealed that the complex undergoes a gradual spin transition in the temperature range of 150-270 K. A mixed-valence complex, [FeII(H3L)][FeIII(L)]- (BF4)2-1.5H2O, was prepared by the controlled deprotonation of the protonated species, [FeII(H3L)](BF4)2-1.5H2O, under aerobic conditions, and the X-ray structure was determined at 293 K. Two species, [FeII(H3L)]2+ and [FeIII(L)], are linked by imidazole-imidazolate (NH-N) hydrogen bonds to form a puckered sheet structure. Magnetic susceptibility measurements and Mössbauer spectra provided an evidence for spin-crossover at both the FeII and FeIII sites. There are three accessible electronic states: (LS FeII-LS FeIII), (HS FeII-LS FeIII), and (HS FeII-HS FeIII) that occur in passing from lower to higher temperatures.

Original languageEnglish
Pages (from-to)191-198
Number of pages8
JournalMaterials Science- Poland
Volume21
Issue number2
Publication statusPublished - 2003

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Keywords

  • Hydrogen bonds
  • Spin crossover
  • Tripodal ligand

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Ohta, H., Sunatsuki, Y., Ikuta, Y., Matsumoto, N., Iijima, S., Akashi, H., Kambe, T., & Kojevia, M. (2003). Spin crossover in a supramolecular FeII-FeIII system. Materials Science- Poland, 21(2), 191-198.