Continuous-wave EPR at 275GHz: Application to high-spin Fe3+ systems

Mathies, Guinevere; Blok, H.; Disselhorst, J.A.J.M.; Gast, P.; Meer, Harmen van der; Miedema, D.M.; Almeida, Rui M.; Moura, José J. G.; Hagen, Wilfred R.; Groenen, E. J. J.

doi:10.1016/j.jmr.2011.03.009

Cited by 24 publications

(15 citation statements)

References 37 publications

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“…Continuous‐wave (cw) EPR spectra were recorded at 275.7 GHz using a home‐built spectrometer at Leiden University, using a probe specially developed to record the extremely broad spectra of high spin Fe‐systems in cw mode . A TE 011 resonator was used for detection of the EPR signal allowing a sample volume of 20 nL.…”

Section: Methodsmentioning

confidence: 99%

The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere

et al. 2018

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The synthesis and characterization of complex [Fe{(SePPh 2 ) 2 N} 2 ] (1) is described. X-ray crystallography shows that this system contains a tetrahedral FeSe 4 coordination sphere. The structural features of 1 are compared with those of similar first row transition element complexes, including a recently reported preparation of [Fe{(SePPh 2 ) 2 N} 2 ] (1 SP ) exhibiting a highly unusual square planar FeSe 4 coordination sphere. The [a] 713 electronic structure of 1 was elucidated by magnetometry, high-frequency EPR, and Mössbauer spectroscopic studies, which reveal zero-field splitting (ZFS) parameters typical of high spin S = 2 tetrahedral Fe II sites. Accurate ZFS parameters (D = +8.22 cm -1 , E/D = 0.104) were obtained by analysis of the EPR spectra and compared with those of the analogous [Fe{(SPPh 2 ) 2 N} 2 ] complex.its active site have been investigated. [6] The effects of replacing Cys by Se-Cys have been investigated in various metalloproteins, such as metallothionein, [7] Cyt P 450 , [8] azurin, [9] and sulfite oxidase. [10] Moreover, sulfide S 2has been replaced by selenide Se 2in the iron-sulfur active site of numerous proteins, [11] like the [4Fe-4S] cluster of [FeFe]-hydrogenase [12a] (Se/S substitution has also been carried out in the [2Fe] cluster of the latter [12b] ), the iron protein of nitrogenase, [13] the photosystem I polypeptide PsaC, [14] aconitase, [15] high potential ironsulfur protein, [16] as well as [2Fe-2S] [17] and 2[4Fe-4S] ferredoxins. [18] As far as the synthetic bioinorganic chemistry of selenium is concerned, a range of multinuclear clusters containing iron coordinated to Se 2and various thiols, [19] as well as tungsteniron-sulfur/selenium clusters, [20] have been investigated by Holm and co-workers. The coordination of selenium to transition metals has also been explored by employing the so called dichalcogenidoimidodiphosphinato ligands, R 2 P(E)NHP(E′)R′ 2 (E, E′ = O, S, Se, Te; R, R ′ = alkyl or aryl groups). [21] Among this family of chelating ligands, L = [Ph 2 P(Se)NP(Se)Ph 2 ] -, [22] containing E = E′ = Se as donor atoms, and R = R′ = Ph as peripheral groups bonded to the P atoms of the P-N-P backbone, has afforded the following structurally characterized homoleptic complexes with first series transition metal ions (structures deposited in the Cambridge Structural Database, CSD [23] ): octahedral M III L 3 , M = V, [24] Cr, [24] tetrahedral M II L 2 , M = Mn, [25] Co, [26] Zn, [27] square planar Ni II L 2 [28] and tetranuclear [Cu I 4 L 3 ]BF 4 . [29] With respect to the coordination of [Ph 2 P(Se)NP(Se)Ph 2 ]to Fe II , it should first be noted that the following literature complexes have been shown, by X-ray crystallography, to unequivocally contain a tetrahedral FeSe 4 coordination sphere: [N(CH 3 CH 2 ) 4 ] 2 [Fe(SePh) 4 ], [30] [Fe(1,10-phen) 3 ][Fe(SePh) 4 ], [31] Eur. J. Inorg. Chem. 2018, 713-721 www.eurjic.org

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Section: Methodsmentioning

confidence: 99%

The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere

et al. 2018

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“…For the J-band experiments a suprasil sample tube of inner diameter 0.15 mm was used (VitroCom Inc.). The effective sample volume, determined by the microwave cavity, is approximately 20 nL [26]. The sample tube was filled with silicon grease to fix the crystal at low temperatures.…”

Section: Sample Preparationmentioning

confidence: 99%

High-frequency EPR study of the high-spin FeII complex Fe[(SPPh2)2N]2

Mathies

Chatziefthimiou

Maganas

et al. 2012

Journal of Magnetic Resonance

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“…38 275 GHz (J band). J-band EPR spectra were obtained on a spectrometer constructed by Blok et al [39][40][41] The operating frequency is 275.7 GHz and the maximum microwave power output is approximately 1 mW. A single-mode TE 011 resonator focusses the microwave field over a sample volume of approximately 20 nL.…”

Section: Synthesis Of the Polarizing Agentsmentioning

confidence: 99%

Conformation of bis-nitroxide polarizing agents by multi-frequency EPR spectroscopy

Soetbeer

Gast

Walish

et al. 2018

Phys. Chem. Chem. Phys.

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Continuous-wave EPR at 275GHz: Application to high-spin Fe3+ systems

Cited by 24 publications

References 37 publications

The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere

The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere

High-frequency EPR study of the high-spin FeII complex Fe[(SPPh2)2N]2

Conformation of bis-nitroxide polarizing agents by multi-frequency EPR spectroscopy

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Continuous-wave EPR at 275GHz: Application to high-spin Fe3+ systems

Cited by 24 publications

References 37 publications

The [Fe{(SePPh2)2N}2] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral FeIISe4 Coordination Sphere

The [Fe{(SePPh2)2N}2] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral FeIISe4 Coordination Sphere

High-frequency EPR study of the high-spin FeII complex Fe[(SPPh2)2N]2

Conformation of bis-nitroxide polarizing agents by multi-frequency EPR spectroscopy

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Product

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The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere

The [Fe{(SePPh₂)₂N}₂] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral Fe^IISe₄ Coordination Sphere