Synthesis, structures, and magnetic properties of iron(II) complexes, [Fe II(HL Me) 2](ClO 4) 2 and its ethanol adduct [Fe II(HL Me) 2](ClO 4) 2·EtOH (HL Me = 2-methylimidazol-4-yl- methylideneamino-2-ethylpyridine): Their structural distortion and spin states

Hiroaki Hagiwara, Suguru Yamauchi, Naohide Matsumoto, Yukinari Sunatsuki

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Two new iron(II) complexes, [Fe II(HL Me) 2](ClO 4) 2 (1) and its ethanol adduct [Fe II(HL Me) 2](ClO 4) 2· EtOH (2) were synthesized by selective crystallization in methanol and ethanol, respectively, where HL Me is a tridentate N 3 ligand, 2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine, and their structures and magnetic properties were investigated. Each compound contains the same octahedrally N 6 coordinated complex-cation [Fe II(HL Me) 2] 2+ and two ClO 4 - ions. The non-solvated compound 1 is the HS (S = 2) complex without spin transition over the 5-300 K temperature range, and has the homochiral 1D helical-chain structure constructed of the intermolecular NH·· ·O - hydrogen bonds between ClO 4 - ions and neighboring imidazole NH groups of the [Fe II(HL Me) 2] 2+ cations. The ethanol adduct 2 shows a gradual one-step spin transition between the HS (S = 2) and LS (S = 0) states, and has two crystallographically independent iron(II) sites with two NH(imidazole)···OH(EtOH)···O(ClO 4 -) hydrogen bonds of Fe(1) site and two NH(imidazole)···O(ClO 4 -) hydrogen bonds of Fe(2) site. There are no further intermolecular interactions to produce an extended structure in a crystal lattice of 2. The presence or absence of thermal spin transition is related to the structural distortion of each HS molecule of these perchlorate salts associated with their surroundings of intermolecular hydrogen bonds.

Original languageEnglish
Pages (from-to)110-116
Number of pages7
Issue number1
Publication statusPublished - Nov 14 2012



  • Crystal solvent
  • Hydrogen bond
  • Iron(II) complex
  • Spin crossover
  • Structural distortion

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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