NH/pi interaction in a spin-crossover complex [FeII(HLMe)2](BPh4)2.2CH3CN (BPh4-=Tetraphenylborate; HLMe=2-Methylimidazol-4-yl-methylideneamino-2-ethylpyridine)

Inorg Chem. 2005 Dec 12;44(25):9288-92. doi: 10.1021/ic051215i.

Abstract

Three FeII complexes, [Fe(HLR)2](BPh4)2.solvent (R=H, Me, Ph), were synthesized, where BPh4-=tetraphenylborate and HLR=2-substituted-imidazol-4-yl-methylideneamino-2-ethylpyridine. The magnetic susceptibility measurements in 5-300 K revealed that [Fe(HLH)2](BPh4)2.H2O, [Fe(HLMe)2](BPh4)2.2CH3CN, and [Fe(HLPh)2](BPh4)2.CH3CN are low-spin (LS), spin-crossover (SC), and high-spin (HS) FeII complexes, respectively, indicating that the spin state can be effectively tuned by the bulkiness of the substituent. Complex shows a steep SC around 250 K, where it assumes a cyclic structure of {[Fe(HLMe)2]BPh4}2 constructed by four NH/pi bonds between the imidazole group and the phenyl ring of BPh4- in the HS state and a deformed structure with NH/pi bonds and linear CH3CN...HN hydrogen bonds at the terminals in the LS state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallization
  • Crystallography, X-Ray
  • Ferrous Compounds / chemical synthesis
  • Ferrous Compounds / chemistry*
  • Imidazoles / chemistry*
  • Iron / chemistry*
  • Magnetics
  • Models, Molecular
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Pyridines / chemistry*
  • Temperature
  • Tetraphenylborate / chemistry*

Substances

  • 2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine
  • Ferrous Compounds
  • Imidazoles
  • Organometallic Compounds
  • Pyridines
  • iron(II)(2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine)2(tetraphenylborate)2.2CH3CN
  • Tetraphenylborate
  • Iron