In:
Dalton Transactions, Royal Society of Chemistry (RSC), Vol. 51, No. 6 ( 2022), p. 2338-2345
Abstract:
From the reaction of 2-hydroxy-6-methylpyridine (L) with iron( ii ) tetrafluoroborate, a new mononuclear iron( iii ) octahedral complex [FeL 6 ](BF 4 ) 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 [FeL 6 ](BF 4 ) 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.
Type of Medium:
Online Resource
ISSN:
1477-9226
,
1477-9234
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
1472887-4
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