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A mononuclear iron(iii) complex with unusual changes of color and magneto-structural properties with temperature : Synthesis, structure, magnetization, multi-frequency ESR and DFT study

Garg, Nitish Kumar LU ; Goriya, Yogesh LU ; Manojveer, Seetharaman LU ; Muratović, Senada ; Pajić, Damir ; Cetina, Mario ; Petreska, Irina ; Krupskaya, Yulia ; Kataev, Vladislav and Johnson, Magnus T. LU , et al. (2022) In Dalton Transactions 51(6). p.2338-2345
Abstract

From the reaction of 2-hydroxy-6-methylpyridine (L) with iron(ii) tetrafluoroborate, a new mononuclear iron(iii) octahedral complex [FeL6](BF4)3 has been isolated. The color of the complex reversibly changed from red at room temperature to yellow-orange at the liquid nitrogen temperature. Magnetization measurements indicate that iron(iii) in [FeL6](BF4)3 is in a high-spin state S = 5/2, from room temperature to 1.8 K. The high-spin ground state of iron(iii) is also confirmed by DFT calculations. Although the spin-crossover of the complex is not observed, X-band and multifrequency high-field/high-frequency electron spin resonance (ESR) spectroscopy shows rather uncommon iron(iii) spectra at room temperature and an unusual change with... (More)

From the reaction of 2-hydroxy-6-methylpyridine (L) with iron(ii) tetrafluoroborate, a new mononuclear iron(iii) octahedral complex [FeL6](BF4)3 has been isolated. The color of the complex reversibly changed from red at room temperature to yellow-orange at the liquid nitrogen temperature. Magnetization measurements indicate that iron(iii) in [FeL6](BF4)3 is in a high-spin state S = 5/2, from room temperature to 1.8 K. The high-spin ground state of iron(iii) is also confirmed by DFT calculations. Although the spin-crossover of the complex is not observed, X-band and multifrequency high-field/high-frequency electron spin resonance (ESR) spectroscopy shows rather uncommon iron(iii) spectra at room temperature and an unusual change with cooling. Spectral simulations reveal that the S = 5/2 ground state multiplet of the complex can be characterized by the temperature independent axial zero-field splitting parameter of |D| = +2 GHz (0.067 cm-1) while the value of the rhombic parameter E of the order of some tenths MHz increases on lowering the temperature. Single crystal X-ray diffraction (SCXRD) shows that the iron(iii) coordination geometry does not change with temperature while supramolecular interactions are temperature dependent, influencing the iron(iii) rhombicity. Additionally, the DFT calculations show temperature variation of the HOMO-LUMO gap, in agreement with the changes of color and ESR-spectra of the iron(iii) complex with temperature.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Dalton Transactions
volume
51
issue
6
pages
8 pages
publisher
Royal Society of Chemistry
external identifiers
  • pmid:35043132
  • scopus:85124438520
ISSN
1477-9226
DOI
10.1039/d1dt03751j
language
English
LU publication?
yes
id
3c56d2cc-a639-48fe-acbb-e51edd088580
date added to LUP
2022-12-30 09:10:06
date last changed
2024-06-24 07:49:40
@article{3c56d2cc-a639-48fe-acbb-e51edd088580,
  abstract     = {{<p>From the reaction of 2-hydroxy-6-methylpyridine (L) with iron(ii) tetrafluoroborate, a new mononuclear iron(iii) octahedral complex [FeL6](BF4)3 has been isolated. The color of the complex reversibly changed from red at room temperature to yellow-orange at the liquid nitrogen temperature. Magnetization measurements indicate that iron(iii) in [FeL6](BF4)3 is in a high-spin state S = 5/2, from room temperature to 1.8 K. The high-spin ground state of iron(iii) is also confirmed by DFT calculations. Although the spin-crossover of the complex is not observed, X-band and multifrequency high-field/high-frequency electron spin resonance (ESR) spectroscopy shows rather uncommon iron(iii) spectra at room temperature and an unusual change with cooling. Spectral simulations reveal that the S = 5/2 ground state multiplet of the complex can be characterized by the temperature independent axial zero-field splitting parameter of |D| = +2 GHz (0.067 cm-1) while the value of the rhombic parameter E of the order of some tenths MHz increases on lowering the temperature. Single crystal X-ray diffraction (SCXRD) shows that the iron(iii) coordination geometry does not change with temperature while supramolecular interactions are temperature dependent, influencing the iron(iii) rhombicity. Additionally, the DFT calculations show temperature variation of the HOMO-LUMO gap, in agreement with the changes of color and ESR-spectra of the iron(iii) complex with temperature.</p>}},
  author       = {{Garg, Nitish Kumar and Goriya, Yogesh and Manojveer, Seetharaman and Muratović, Senada and Pajić, Damir and Cetina, Mario and Petreska, Irina and Krupskaya, Yulia and Kataev, Vladislav and Johnson, Magnus T. and Wendt, Ola F. and Žilić, Dijana}},
  issn         = {{1477-9226}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{6}},
  pages        = {{2338--2345}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Dalton Transactions}},
  title        = {{A mononuclear iron(iii) complex with unusual changes of color and magneto-structural properties with temperature : Synthesis, structure, magnetization, multi-frequency ESR and DFT study}},
  url          = {{http://dx.doi.org/10.1039/d1dt03751j}},
  doi          = {{10.1039/d1dt03751j}},
  volume       = {{51}},
  year         = {{2022}},
}