Probing Physical Oxidation State by Resonant X‐ray Emission Spectroscopy: Applications to Iron Model Complexes and Nitrogenase

Castillo, Rebeca G.; Hahn, Anselm W.; Kuiken, Benjamin E. Van; Henthorn, Justin T.; McGale, Jeremy; DeBeer, Serena

doi:10.1002/anie.202015669

Cited by 30 publications

(51 citation statements)

References 80 publications

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“…We have synthesized and structurally characterized (Fig. 2 ) a series of [L 2 Fe 2 Q 2 ] − dimers (with tetrahydrofuran (THF)-solvated K + counter ions) supported by a β-diketiminate ligand (L − ), where the bridging µ-Q 2– ligands are S 2– ( 1 ) 27 , Se 2– ( 2 ) and Te 2– ( 3 ). To the best of our knowledge, compound 3 is the first reported synthesis of an [Fe 2 Te 2 ] + complex.…”

Section: Resultsmentioning

confidence: 99%

“…57 Fe metal was purchased from EurIsotop (Cambridge Isotope Laboratories) and used as received. SePMe 3 , TePCy 3 (Cy = cyclohexyl), LH, 57 FeCl 2 , LFe(PhMe), L 2 Fe 2 S 2 ( 1 ox ) and [K(THF) 6 ][L 2 Fe 2 S 2 ]·2THF ( 1 ) were prepared as previously reported 27 , 46 – 50 .…”

Section: Methodsmentioning

confidence: 99%

“…This compound was prepared analogously to the non-isotopically labelled 1 as previously reported with L 2 57 Fe 2 S (0.1254 g, 0.128 mmol) and SSbPh 3 (0.0497 g, 0.129 mmol) to afford 0.0293 g (23%) of the crude isotopically labelled diferric 57 1 ox (L 2 57 Fe 2 S 2 ) 27 . Reduction was accomplished with KC 8 (0.0054 g, 0.040 mmol) and C 10 H 8 (0.0048 g, 0.037 mmol) to afford 0.0122 g of 57 1 as dark-red crystals in 6% overall yield.…”

Section: Methodsmentioning

confidence: 99%

“… 61 ). The X-ray emission spectrum for complex 1 has been previously reported 27 . Sample preparation and experimental details for complexes 2 and 3 are described below.…”

Section: Methodsmentioning

confidence: 99%

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Stabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes

et al. 2022

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The electronic structure and ground spin states, S, observed for mixed-valent iron–sulfur dimers (FeII-FeIII) are typically determined by the Heisenberg exchange interaction, J, that couples the magnetic interaction of the two metal centres either ferromagnetically (J > 0, S = 9/2) or antiferromagnetically (J < 0, S = 1/2). In the case of antiferromagnetically coupled iron centres, stabilization of the high-spin S = 9/2 ground state is also feasible through a Heisenberg double-exchange interaction, B, which lifts the degeneracy of the Heisenberg spin states. This theorem also predicts intermediate spin states for mixed-valent dimers, but those have so far remained elusive. Herein, we describe the structural, electron paramagnetic resonance and Mössbauer spectroscopic, and magnetic characterization of a series of mixed-valent complexes featuring [Fe2Q2]+ (Q = S2–, Se2–, Te2–), where the Se and Te complexes favour S = 3/2 spin states. The incorporation of heavier chalcogenides in this series reveals a delicate balance of antiferromagnetic coupling, Heisenberg double-exchange and vibronic coupling.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“… 61 ). The X-ray emission spectrum for complex 1 has been previously reported 27 . Sample preparation and experimental details for complexes 2 and 3 are described below.…”

Section: Methodsmentioning

confidence: 99%

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Stabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes

et al. 2022

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“… 56 , 57 Furthermore, we have demonstrated that Se Kβ HERFD XAS exhibits spectral resolution matching Se Kα HERFD XAS, and thus a single experimental setup allows access to complementary Se VtC XES and HERFD XAS measurements. Future studies will explore resonant measurements as a means of enhancing sensitivity to changes in Se chemical and electronic structure—analogous to recent Fe resonant X-ray emission spectroscopic studies 58 —as well as the feasibility of laboratory-based Se X-ray emission measurements.…”

Section: Discussionmentioning

confidence: 99%

Selenium Valence-to-Core X-ray Emission Spectroscopy and Kβ HERFD X-ray Absorption Spectroscopy as Complementary Probes of Chemical and Electronic Structure

Henthorn

DeBeer

2022

Inorg. Chem.

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Selenium X-ray absorption spectroscopy (XAS) has found widespread use in investigations of Se-containing materials, geochemical processes, and biologically active sites. In contrast to sulfur Kβ X-ray emission spectroscopy (XES), which has been found to contain electronic and structural information complementary to S XAS, Se Kβ XES remains comparatively underexplored. Herein, we present the first Se Valence-to-Core (VtC) XES studies of reduced Se-containing compounds and FeSe dimers. Se VtC XES is found to be sensitive to changes in covalent Se bonding interactions (Se–Se/Se–C/Se–H bonding) while being relatively insensitive to changes in Fe oxidation states as selenide bridges in FeSe dimers ([Fe 2 Se 2 ] 2+ vs [Fe 2 Se 2 ] + ). In contrast, Se Kβ HERFD XAS is demonstrated to be quite sensitive to changes in the Fe oxidation state with Se Kβ HERFD XAS demonstrating experimental resolution equivalent to Kα HERFD XAS. Additionally, computational studies reveal both Se VtC XES and XAS to be sensitive to selenium protonation in FeSe complexes.

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Surface Boron Modulation on Cobalt Oxide Nanocrystals for Electrochemical Oxygen Evolution Reaction

Weidenthaler

Wang

et al. 2022

Angewandte Chemie

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Herein, we show that coupling boron with cobalt oxide tunes its structure and significantly boost its electrocatalytic performance for the oxygen evolution reaction (OER). Through a simple precipitation and thermal treatment process, a series of CoÀ B oxides with tunable morphologies and textural parameters were prepared. Detailed structural analysis supported first the formation of an disordered and partially amorphous material with nanosized Co 3 BO 5 and/or Co 2 B 2 O 6 being present on the local atomic scale. The boron modulation resulted in a superior OER reactivity by delivering a large current and an overpotential of 338 mV to reach a current density of 10 mA cm À 2 in 1 M KOH electrolyte. Identical location transmission electron microscopy and in situ electrochemical Raman spectroscopy studies revealed alteration and surface re-construction of materials, and formation of CoO 2 and (oxy)hydroxide intermediate, which were found to be highly dependent on crystallinity of the samples.

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Probing Physical Oxidation State by Resonant X‐ray Emission Spectroscopy: Applications to Iron Model Complexes and Nitrogenase

Cited by 30 publications

References 80 publications

Stabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes

Stabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes

Selenium Valence-to-Core X-ray Emission Spectroscopy and Kβ HERFD X-ray Absorption Spectroscopy as Complementary Probes of Chemical and Electronic Structure

Surface Boron Modulation on Cobalt Oxide Nanocrystals for Electrochemical Oxygen Evolution Reaction

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