Towards a comprehensive X-ray approach for studying the photosynthetic manganese complex–XANES, Kα/Kβ/Kβ-satellite emission lines, RIXS, and comparative computational approaches for selected model complexes

Zaharieva, Ivelina; Chernev, Petko; Risch, Marcel; Gerencsér, László; Berggren, Gustav; Shevchenko, Denys; Anderlund, Magnus F.; Weng, Tsu‐Chien; Haumann, Michael; Dau, Holger

doi:10.1088/1742-6596/190/1/012142

Cited by 15 publications

(19 citation statements)

References 29 publications

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“…The low emission intensity in the Kß′ region indicates the absence of unpaired spins on the formal Fe(I) (d 7 ) ions in 1. 53,58,68,71,105 This shows that spin pairing occurs to yield a singlet ground state (M = 1), in agreement with previous results for diiron compounds. 58 Accordingly, this multiplicity has been employed in the DFT calculations of the XAS/XES spectra.…”

Section: Journal Of the American Chemical Societysupporting

confidence: 91%

Electronic Structure of an [FeFe] Hydrogenase Model Complex in Solution Revealed by X-ray Absorption Spectroscopy Using Narrow-Band Emission Detection

et al. 2012

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High-resolution X-ray absorption spectroscopy with narrow-band X-ray emission detection, supported by density functional theory calculations (XAES-DFT), was used to study a model complex, ([Fe(2)(μ-adt)(CO)(4)(PMe(3))(2)] (1, adt = S-CH(2)-(NCH(2)Ph)-CH(2)-S), of the [FeFe] hydrogenase active site. For 1 in powder material (1(powder)), in MeCN solution (1'), and in its three protonated states (1H, 1Hy, 1HHy; H denotes protonation at the adt-N and Hy protonation of the Fe-Fe bond to form a bridging metal hydride), relations between the molecular structures and the electronic configurations were determined. EXAFS analysis and DFT geometry optimization suggested prevailing rotational isomers in MeCN, which were similar to the crystal structure or exhibited rotation of the (CO) ligands at Fe1 (1(CO), 1Hy(CO)) and in addition of the phenyl ring (1H(CO,Ph), 1HHy(CO,Ph)), leading to an elongated solvent-exposed Fe-Fe bond. Isomer formation, adt-N protonation, and hydride binding caused spectral changes of core-to-valence (pre-edge of the Fe K-shell absorption) and of valence-to-core (Kß(2,5) emission) electronic transitions, and of Kα RIXS data, which were quantitatively reproduced by DFT. The study reveals (1) the composition of molecular orbitals, for example, with dominant Fe-d character, showing variations in symmetry and apparent oxidation state at the two Fe ions and a drop in MO energies by ~1 eV upon each protonation step, (2) the HOMO-LUMO energy gaps, of ~2.3 eV for 1(powder) and ~2.0 eV for 1', and (3) the splitting between iron d(z(2)) and d(x(2)-y(2)) levels of ~0.5 eV for the nonhydride and ~0.9 eV for the hydride states. Good correlations of reduction potentials to LUMO energies and oxidation potentials to HOMO energies were obtained. Two routes of facilitated bridging hydride binding thereby are suggested, involving ligand rotation at Fe1 for 1Hy(CO) or adt-N protonation for 1HHy(CO,Ph). XAES-DFT thus enables verification of the effects of ligand substitutions in solution for guided improvement of [FeFe] catalysts.

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Section: Journal Of the American Chemical Societysupporting

confidence: 91%

Electronic Structure of an [FeFe] Hydrogenase Model Complex in Solution Revealed by X-ray Absorption Spectroscopy Using Narrow-Band Emission Detection

et al. 2012

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“…The opposite effect can be seen at the oxygen K-edge, where the peaks are shied to lower photon energies. These results agree very well with synchrotron studies by Cramer et al 31 and Zaharieva et al 32 reporting an average positional change of 1.1 eV per increment in oxidation state. The energy values of the Mn L-edge peaks differ less than 0.5% from these literature data.…”

Section: Nexafs Measurementssupporting

confidence: 92%

Laboratory-scale near-edge X-ray absorption fine structure spectroscopy with a laser-induced plasma source

Müller

Schellhorn

Mann

2019

J. Anal. At. Spectrom.

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“…2) so that the intensity of the Kb 0 relative to the Kb 1,3 intensity increases for an increasing number of unpaired 3d spins. 71,72,97 For non-resonant excitation, promotion of both a and b 1s-electrons into the continuum can occur and the intensity of the Kb 0 emission is large for example for high-spin (hs) d 6 Fe(II) or d 5 Fe(III) species with four or ve unpaired 3d a-spins and small for example for low-spin (ls) d 6 Fe(II) species with zero unpaired 3d spins. Notably, for ls diironcarbonyl complexes with formal d 7 Fe(I) states, the surplus d-electrons usually pair, so that the Kb 0 emission is similarly small as that of ls d 6 Fe(II) compounds.…”

Section: Resultsmentioning

confidence: 99%

Electronic and molecular structures of the active-site H-cluster in [FeFe]-hydrogenase determined by site-selective X-ray spectroscopy and quantum chemical calculations

et al. 2014

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Towards a comprehensive X-ray approach for studying the photosynthetic manganese complex–XANES, Kα/Kβ/Kβ-satellite emission lines, RIXS, and comparative computational approaches for selected model complexes

Cited by 15 publications

References 29 publications

Electronic Structure of an [FeFe] Hydrogenase Model Complex in Solution Revealed by X-ray Absorption Spectroscopy Using Narrow-Band Emission Detection

Electronic Structure of an [FeFe] Hydrogenase Model Complex in Solution Revealed by X-ray Absorption Spectroscopy Using Narrow-Band Emission Detection

Laboratory-scale near-edge X-ray absorption fine structure spectroscopy with a laser-induced plasma source

Electronic and molecular structures of the active-site H-cluster in [FeFe]-hydrogenase determined by site-selective X-ray spectroscopy and quantum chemical calculations

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