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Abstract <p>The earlier described iron(II) complexes [Fe(L<sup>H</sup>)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub> and [Fe(L<sup>F</sup>)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub> are synthesized by simple mixing in an NMR tube of iron(II) perchlorate hexahydrate in deuterated methanol with the corresponding 2,6-bis(pyrazol-3-yl)pyridine containing the phenyl (L<sup>H</sup>) or <i>ortho-</i>difluorophenyl (L<sup>F</sup>) group in the first position of the pyrazolyl fragment and capable of deprotonating the hydroxy group in the fifth position. The complexes exist in the high-spin state according to an analysis of the temperature dependences of the chemical shifts of their signals in the <sup>1</sup>H NMR spectra. Using the same approach, a possibility of the in situ reversible deprotonation of the pH-sensitive hydroxy groups in the ligands under the action of 1,8-diazabicyclo[5.4.0]undec-7-ene is demonstrated. A possibility of spin equilibrium shifting due to deprotonation is checked.</p>

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Analysis of the Spin State of the Iron Complexes with Hydroxysubstituted 2,6-Bis(pyrazol-3-yl)pyridines for Deprotonation in Solution

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • E. S. Safiullina,
  • I. A. Nikovskii,
  • Yu. V. Nelyubina

摘要

Abstract

The earlier described iron(II) complexes [Fe(LH)2](ClO4)2 and [Fe(LF)2](ClO4)2 are synthesized by simple mixing in an NMR tube of iron(II) perchlorate hexahydrate in deuterated methanol with the corresponding 2,6-bis(pyrazol-3-yl)pyridine containing the phenyl (LH) or ortho-difluorophenyl (LF) group in the first position of the pyrazolyl fragment and capable of deprotonating the hydroxy group in the fifth position. The complexes exist in the high-spin state according to an analysis of the temperature dependences of the chemical shifts of their signals in the 1H NMR spectra. Using the same approach, a possibility of the in situ reversible deprotonation of the pH-sensitive hydroxy groups in the ligands under the action of 1,8-diazabicyclo[5.4.0]undec-7-ene is demonstrated. A possibility of spin equilibrium shifting due to deprotonation is checked.