Comparative oxidative ability of mononuclear and dinuclear high-valent iron–oxo species towards the activation of methane: does the axial/bridge atom modulate the reactivity?

Ansari, Mursaleem; Rajaraman, Gopalan

doi:10.1039/d2dt02559k

Cited by 5 publications

(4 citation statements)

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“…Consistent with experimental and theoretical data, ,,,, the computed energetics confirm that all Fe(IV)-oxo/hydroxo models have an intermediate spin ( S = 1) ground state, well-separated from either the low or the high spin alternatives (Tables S2 and S3). The ground state prediction is uniformly consistent between DFT and high-level DLPNO-CCSD(T) calculations, − with the two approaches differing in the relative ordering of the excited S = 2 and S = 0 states, a topic that is however of no concern here. The calculated spin density plots for all 16 model ground states are shown in Figure S3, and the spin populations are listed in Table S4.…”

Section: Resultsmentioning

confidence: 99%

Correlating Structure with Spectroscopy in Ascorbate Peroxidase Compound II

Ansari,

Bhattacharjee,

Pantazis

2024

J. Am. Chem. Soc.

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Structural and spectroscopic investigations of compound II in ascorbate peroxidase (APX) have yielded conflicting conclusions regarding the protonation state of the crucial Fe(IV) intermediate. Neutron diffraction and crystallographic data support an iron(IV)hydroxo formulation, whereas Mossbauer, X-ray absorption (XAS), and nuclear resonance vibrational spectroscopy (NRVS) studies appear consistent with an iron(IV)-oxo species. Here we examine APX with spectroscopy-oriented QM/MM calculations and extensive exploration of the conformational space for both possible formulations of compound II. We establish that irrespective of variations in the orientation of a vicinal arginine residue and potential reorganization of proximal water molecules and hydrogen bonding, the Fe−O distances for the oxo and hydroxo forms consistently fall within distinct, narrow, and nonoverlapping ranges. The accuracy of geometric parameters is validated by coupled-cluster calculations with the domain-based local pair natural orbital approach, DLPNO-CCSD(T). QM/MM calculations of spectroscopic properties are conducted for all structural variants, encompassing Mossbauer, optical, X-ray absorption, and X-ray emission spectroscopies and NRVS. All spectroscopic observations can be assigned uniquely to an Fe(IV)�O form. A terminal hydroxy group cannot be reconciled with the spectroscopic data. Under no conditions can the Fe(IV)�O distance be sufficiently elongated to approach the crystallographically reported Fe−O distance. The latter is consistent only with a hydroxo species, either Fe(IV) or Fe(III). Our findings strongly support the Fe(IV)�O formulation of APX-II and highlight unresolved discrepancies in the nature of samples used across different experimental studies.

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Section: Resultsmentioning

confidence: 99%

Correlating Structure with Spectroscopy in Ascorbate Peroxidase Compound II

Ansari,

Bhattacharjee,

Pantazis

2024

J. Am. Chem. Soc.

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“…Furthermore, the natural bond orbital (NBO) study of the title molecule 3 and 3-CN was computed at the B3LYP/6-31g level of the model. 41 This analysis aimed to elucidate electron density delocalization and intra-and inter-molecular bonding, and explore charge transfer (CT) or the extent of conjugative interaction between the benzithiazolyl and 3-pyrrolyl BODIPY units in compound 3. Second-order perturbation theory, applied to the Fock matrix, was utilized to evaluate donor-acceptor interactions in the NBO investigation.…”

Section: Dft/td-dft Studiesmentioning

confidence: 99%

An α-benzithiazolyl 3-pyrrolyl BODIPY probe for ratiometric selective sensing of cyanide ions and bioimaging studies

Behera,

Mohanty,

Ravikanth

2024

Phys. Chem. Chem. Phys.

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“…Our hypothesis is supported by the study of arylruthenium(III) porphyrin, which was found to be highly active catalysts for hydrocarbon oxidation [45] . Closely related systems employing Fe cations have also been investigated in context of methane oxidation by Ansari and co‐workers [46,47] . The authors found that the typically high energy barrier for the C−H bond activation can be significantly reduced in the case of Fe binuclear complex, what allows the reaction to occur via the excited intermediate.…”

Section: Introductionmentioning

confidence: 99%

Partial Methane Oxidation to Methanol on Ru‐Porphyrins – on the Role of Non‐Innocent Ligands and Spin Crossover

Kizior,

Jezierska,

Szyja

2023

ChemPhysChem

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The partial oxidation reaction of CH4 led to the formation of CH3OH in the presence of Ru‐porphyrin oxo complexes (denoted as POR, POR‐O and POR‐OH where in the case of the last two, oxygen atom and the OH group were attached to the active site, respectively), in which Ru was present on different oxidation states. The simulations were performed based on Density Functional Theory (DFT) with extended geometric and electronic structure analyses of each reaction step. Moreover, the reaction pathways were investigated in different spin states. The Spin Crossover (SCO) phenomenon was found to play an important role in the kinetics of the reaction in the presence of POR and POR‐O. Harmonic Oscillator Model of Aromaticity (HOMA) index was applied for different spin states to estimate the aromaticity changes of the pyrrole rings in the Ru‐porphyrin complexes. In order to characterize the nature of bonding, the Natural Bond Orbitals (NBO) analysis including the Wiberg Bond Index (WBI) and Natural Population Analysis (NPA) was carried out. Finally, the Non‐Covalent Interactions (NCI) index was employed to gain insight into interactions between the components of the reaction. It was found that the non‐covalent interactions cannot be neglected in the studied reaction paths.

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Comparative oxidative ability of mononuclear and dinuclear high-valent iron–oxo species towards the activation of methane: does the axial/bridge atom modulate the reactivity?

Abstract: Over the years, mononuclear FeIV=O species have been extensively studied, but the presence of dinuclear FeIV=O species in soluble methane monooxygenase (sMMO) inspired the development of biomimic models that could...

Cited by 5 publications

References 144 publications

Correlating Structure with Spectroscopy in Ascorbate Peroxidase Compound II

Correlating Structure with Spectroscopy in Ascorbate Peroxidase Compound II

An α-benzithiazolyl 3-pyrrolyl BODIPY probe for ratiometric selective sensing of cyanide ions and bioimaging studies

Partial Methane Oxidation to Methanol on Ru‐Porphyrins – on the Role of Non‐Innocent Ligands and Spin Crossover

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