Supramolecular spin-crossover iron complexes based on imidazole-imidazolate hydrogen bonds

Yukinari Sunatsuki, Hiromi Ohta, Masaaki Kojima, Yuichi Ikuta, Yoshiyuki Goto, Naohide Matsumoto, Seiichiro Iijima, Haruo Akashi, Sumio Kaizaki, Françoise Dahan, Jean Pierre Tuchagues

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125 Citations (Scopus)

Abstract

The [FeII(H3L)](BF4)2· 3H2O (1) complex was synthesized, where H3L (tris{[2-{(imidazole-4-yl)methylidene}amino]ethyl}amine) is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole (fim) in a 1:3 molar ratio. Starting from 1, a series of complexes, [Fe II(H1.5L)](BF4)0.5 (2) (=[Fe II(H3L)][FeII(L)]BF4), [Fe-(H 1.5L)]BF4 (3) (=[FeII(H3L)][Fe III(L)](BF4)2), [FeIII(H 3L)](BF4)3·fim·H2O (4), and [FeIII(L)]·2.5H2O (5), has been synthesized and characterized. The single-crystal X-ray structure of each complex has been determined. The FeII compound, 2, and a mixed valence FeII-FeIII compound, 3, involve formally hemi-deprotonated ligands, H1.5L. The structure of 3 consists of a homochiral two-dimensional assembled sheet, arising from the intermolecular hydrogen bonds between [FeII(H3L)]2+ and [FeIII(L)]0 (3). All but 5 exhibit spin crossover between low-spin (LS) and high-spin (HS) states. This is a rare case where both Fe II and FeIII complexes containing the same ligand exhibit spin-crossover behavior. Magnetic susceptibility and Mössbauer studies showed that 3 has three accessible electronic states: LS FeII-LS FeIII, HS FeII-LS FeIII, and HS Fe II-HS FeIII. Compounds 1-3 show the light-induced excited spin-state trapping effect at the FeII sites upon irradiation with green light. The solution magnetic properties, electronic spectra, and electrochemical properties of 1, 4, and 5 were also studied.

Original languageEnglish
Pages (from-to)4154-4171
Number of pages18
JournalInorganic Chemistry
Volume43
Issue number14
Publication statusPublished - Jul 12 2004

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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    Sunatsuki, Y., Ohta, H., Kojima, M., Ikuta, Y., Goto, Y., Matsumoto, N., Iijima, S., Akashi, H., Kaizaki, S., Dahan, F., & Tuchagues, J. P. (2004). Supramolecular spin-crossover iron complexes based on imidazole-imidazolate hydrogen bonds. Inorganic Chemistry, 43(14), 4154-4171.