scholarly journals Spin states, bonding and magnetism in mixed valence iron(0)–iron(II) complexes

2021 ◽  
Author(s):  
Daniel Kim ◽  
Daniel Wilson ◽  
Majed Fataftah ◽  
Brandon Mercado ◽  
Patrick Holland
Keyword(s):  
High Spin ◽  
Computational Analysis ◽  
Mixed Valence ◽  
Lewis Base ◽  
Zero Field ◽  
Spin States ◽  
Iron Site ◽  
Zero Field Splitting ◽  
Structure Description ◽  
High Spin Iron

We report the synthesis of two complexes featuring unsupported Fe–Fe bonds between a diketiminate/dialdiminate-coordinated iron site and a cyclopentadienyl dicarbonyl iron site. Mössbauer spectroscopy, SQUID magnetometry and computational analysis indicate that the most accurate electronic structure description is with the Fe(CO)2Cp site as low spin iron(0), and it acts as a Lewis base toward the high spin iron(II) of the LFe fragment which is a Lewis acid. In both compounds, the three-coordinate high-spin iron(II) site has large zero-field splitting (zfs), up to D = –50 cm–1.

scholarly journals Analysis of the high-spin states of the 2[4Fe-4Se]+ ferredoxin from Clostridium pasteurianum by Mössbauer spectroscopy

1987 ◽  
Vol 242 (2) ◽  
pp. 525-530 ◽  
Author(s):  
P Auric ◽  
J Gaillard ◽  
J Meyer ◽  
J M Moulis
Keyword(s):  
High Spin ◽  
Field Approximation ◽  
Clostridium Pasteurianum ◽  
Spin Interaction ◽  
Zero Field ◽  
Spin States ◽  
Hyperfine Fields ◽  
Zero Field Splitting ◽  
High Spin States ◽  
Applied Fields

A Mössbauer study of the three spin states of the reduced selenium-substituted 2[4Fe-4Se]+ ferredoxin from Clostridium pasteurianum was carried out at T = 1.6 K, in perpendicular and parallel applied magnetic fields of up to 10 T. In low (0.1 T) applied fields, the spectra of the classical S = 1/2 state exhibit magnetic hyperfine patterns arising from two pairs of iron atoms with opposite hyperfine fields. The S = 7/2 state is in the slow relaxation limit at T less than or equal to 4 K in the absence of applied field. The corresponding Mössbauer spectrum can be understood in terms of anti-parallel coupling between one high-spin Fe3+ ion (Hhf = +21.2 T) and three high-spin Fe2+ ions (Hhf, xy = -25.5 T, Hhf,z = -28.5 T). For the S = 3/2 spin state, the use of high (8-10 T) applied fields was necessary to ensure the validity of the high-field approximation and overcome the intercluster spin-spin interaction. The spectral data obtained under such conditions allowed the determination of the hyperfine field (-4.2 T) and a tentative estimation of the zero-field splitting (D approximately less than 3 cm-1).

Analysis of the EPR spectra of transferrin: the importance of a zero-field-splitting distribution and 4th-order terms

2019 ◽  
Vol 21 (31) ◽  
pp. 16937-16948 ◽  
Author(s):  
Mykhailo Azarkh ◽  
Peter Gast ◽  
Anne B. Mason ◽  
Edgar J. J. Groenen ◽  
Guinevere Mathies
Keyword(s):  
High Spin ◽  
Biological Systems ◽  
New Method ◽  
Epr Spectra ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Effective Use ◽  
High Spin Iron

A new method is implemented to extract the distribution of zero-field-splitting parameters from the EPR spectra of transferrin. This promotes the effective use of multi-frequency EPR to characterize high-spin iron sites in biological systems.

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