Electronic Control of the “Bailar Twist” in Formally d<sup>0</sup>-d<sup>2</sup> Molybdenum Tris(dithiolene) Complexes: A Sulfur K-edge X-ray Absorption Spectroscopy and Density Functional Theory Study

Tenderholt, Adam L.; Szilágyi, Róbert K.; Holm, R. H.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

doi:10.1021/ic800494h

Cited by 56 publications

(130 citation statements)

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“…The Mo tris-dithiolene complexes are included for reference as their electronic structures have already been defined 6. The Mo(IV) complexes (red, top panel) both have significant pre-edge intensity at ~2471.3 eV.…”

Section: Results and Analysismentioning

confidence: 99%

“…The Mo(IV) complexes (red, top panel) both have significant pre-edge intensity at ~2471.3 eV. The pre-edge in the Mo(IV) bis-dithiolene complex (solid) has a shoulder at higher energy (2472.2 eV) while the pre-edge in the Mo(IV) tris-dithiolene (dashed) has a small contribution at lower energy (indicated by a asterisk at 2470.2 eV) due to an oxidized impurity (~10%, see reference 6). In addition, another unresolved pre-edge feature is present in the data of both the bis-and tris-dithiolene complexes at 2473.2 and 2472.7 eV, respectively.…”

Section: Results and Analysismentioning

confidence: 99%

“…ligand-based oxidation) in metal-dithiolene complexes 4–9. For example, formally Mo(VI) tris-dithiolene complexes, in fact, have a metal d 2 electron configuration 6. Molybdenum(VI) sites in the DMSOr family are coordinated by two pterindithiolene cofactors, a protein-derived ligand such as serine, cysteine, or selenocysteine, and has an additional strong oxo ligand (Scheme 1a).…”

Section: Introductionmentioning

confidence: 99%

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Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

et al. 2010

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Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two Mo bis-dithiolene complexes, [Mo(OSi)(bdt) 2 ] 1− and [MoO(OSi)(bdt) 2 ] 1− where OSi = [OSiPh 2 t Bu] 1− and bdt = benzene-1,2-dithiolate(2−), that model the Mo(IV) and Mo(VI)=O states of the DMSO reductase family of molybdenum enzymes. These results show that the Mo(IV) complex undergoes metalbased oxidation unlike the Mo(IV) tris-dithiolene complexes, indicating that the dithiolene ligands are behaving innocently. Experimentally-validated calculations have been extended to model the oxo-transfer reaction coordinate using dimethylsulfoxide (DMSO) as a substrate. The reaction proceeds through a transition state (TS1) to an intermediate with DMSO weakly bound, followed by a subsequent transition state (TS2) which is the largest barrier of the reaction. The factors that control the energies of these transition states, the nature of the oxo transfer process, and the role of the dithiolene ligand are discussed.

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Section: Results and Analysismentioning

confidence: 99%

Section: Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

et al. 2010

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“…8,23–27 X-ray absorption spectroscopy has been used to help identify the covalency of the metal-dithiolene interaction as well as determine the oxidation states for the ligand and metal. 28–31 Gas-phase ultraviolet photoelectron spectroscopy (UPS) studies have shown the leveling effect that dithiolenes have on the valence ionizations. 23,32 Previous valence photoelectron studies of the molecules in Figure 2 have shown that the metal-dithiolene interaction effectively maintains the highest occupied molecular orbital ionization in a narrow energy range, which helps to level the redox potentials between d 2 , d 1 , and d 0 states during a catalytic cycle.…”

Section: Introductionmentioning

confidence: 99%

Metal–Sulfur Valence Orbital Interaction Energies in Metal–Dithiolene Complexes: Determination of Charge and Overlap Interaction Energies by Comparison of Core and Valence Ionization Energy Shifts

et al. 2011

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The electronic interactions between metals and dithiolenes are important in the biological processes of many metalloenzymes as well as in diverse chemical and material applications. Of special note is the ability of the dithiolene ligand to support metal centers in multiple coordination environments and oxidation states. To better understand the nature of metal-dithiolene electronic interactions, new capabilities in gas-phase core photoelectron spectroscopy for molecules with high sublimation temperatures have been developed and applied to a series of molecules of the type Cp2M(bdt) (Cp = η5-cyclopentadienyl, M = Ti, V, Mo, and bdt = benzenedithiolato). Comparison of the gas-phase core and valence ionization energy shifts provides a unique quantitative energy measure of valence orbital overlap interactions between the metal and sulfur orbitals that is separated from the effects of charge redistribution. The results explain the large amount of sulfur character in the redox-active orbitals and the ‘leveling’ of oxidation state energies in metal-dithiolene systems. The experimentally-determined orbital interaction energies reveal a previously unidentified overlap interaction of the predominantly sulfur HOMO of the bdt ligand with filled π orbitals of the Cp ligands, suggesting that direct dithiolene interactions with other ligands bound to the metal could be significant for other metal-dithiolene systems in chemistry and biology.

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“…This increase is much smaller than the increase observed for the tris-dithiolene Mo IV and Mo VI complexes 40 (118%), which undergo a ligand-based redox process (i.e., noninnocent behavior). Thus, for the monooxo Mo IV and bisoxo Mo VI complexes, the presence of oxo ligands leads to innocent behavior of the dithiolenes where the covalent donor bonding to the Mo simply increases upon oxidation of the metal center.…”

Section: Results and Analysismentioning

confidence: 65%

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Calculations on Monooxo Mo^IV and Bisoxo Mo^VI Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in Sulfite Oxidase and Its Relation to the Mechanism of DMSO Reductase

Tenderholt

Holm

et al. 2014

J. Am. Chem. Soc.

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Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two complexes [MoIVO(bdt)2]2– and [MoVIO2(bdt)2]2– (bdt = benzene-1,2-dithiolate(2−)) that relate to the reduced and oxidized forms of sulfite oxidase (SO). These are compared with those of previously studied dimethyl sulfoxide reductase (DMSOr) models. DFT calculations supported by the data are extended to evaluate the reaction coordinate for oxo transfer to a phosphite ester substrate. Three possible transition states are found with the one at lowest energy, stabilized by a P–S interaction, in good agreement with experimental kinetics data. Comparison of both oxo transfer reactions shows that in DMSOr, where the oxo is transferred from the substrate to the metal ion, the oxo transfer induces electron transfer, while in SO, where the oxo transfer is from the metal site to the substrate, the electron transfer initiates oxo transfer. This difference in reactivity is related to the difference in frontier molecular orbitals (FMO) of the metal–oxo and substrate–oxo bonds. Finally, these experimentally related calculations are extended to oxo transfer by sulfite oxidase. The presence of only one dithiolene at the enzyme active site selectively activates the equatorial oxo for transfer, and allows facile structural reorganization during turnover.

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Electronic Control of the “Bailar Twist” in Formally d⁰-d² Molybdenum Tris(dithiolene) Complexes: A Sulfur K-edge X-ray Absorption Spectroscopy and Density Functional Theory Study

Abstract: Sulfur K-edge x-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of a series of Mo tris(dithiolene) complexes, [Mo(mdt)

Cited by 56 publications

References 42 publications

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

Metal–Sulfur Valence Orbital Interaction Energies in Metal–Dithiolene Complexes: Determination of Charge and Overlap Interaction Energies by Comparison of Core and Valence Ionization Energy Shifts

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Calculations on Monooxo Mo^IV and Bisoxo Mo^VI Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in Sulfite Oxidase and Its Relation to the Mechanism of DMSO Reductase

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Electronic Control of the “Bailar Twist” in Formally d0-d2 Molybdenum Tris(dithiolene) Complexes: A Sulfur K-edge X-ray Absorption Spectroscopy and Density Functional Theory Study

Abstract: Sulfur K-edge x-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of a series of Mo tris(dithiolene) complexes, [Mo(mdt)

Cited by 56 publications

References 42 publications

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues

Metal–Sulfur Valence Orbital Interaction Energies in Metal–Dithiolene Complexes: Determination of Charge and Overlap Interaction Energies by Comparison of Core and Valence Ionization Energy Shifts

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Calculations on Monooxo MoIV and Bisoxo MoVI Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in Sulfite Oxidase and Its Relation to the Mechanism of DMSO Reductase

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Electronic Control of the “Bailar Twist” in Formally d⁰-d² Molybdenum Tris(dithiolene) Complexes: A Sulfur K-edge X-ray Absorption Spectroscopy and Density Functional Theory Study

Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Calculations on Monooxo Mo^IV and Bisoxo Mo^VI Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in Sulfite Oxidase and Its Relation to the Mechanism of DMSO Reductase