Iron and manganese oxo complexes, oxo wall and beyond

Larson, Virginia A.; Battistella, Beatrice; Ray, Kallol; Lehnert, Nicolai; Nam, Wonwoo

doi:10.1038/s41570-020-0197-9

Cited by 202 publications

(226 citation statements)

References 174 publications

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“…From the previously studied molecular complexes, reported Raman peak positions for stretching vibrational mode of Mn(IV)-oxo species are between 707 and 803 cm −1 (refs. 46 – 48 ), while those of Mn(V)-oxo species are between 957 and 997 cm −1 (refs. 49 – 51 ).…”

Section: Results and Discussionmentioning

confidence: 99%

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

et al. 2020

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High-valent metal-oxo moieties have been implicated as key intermediates preceding various oxidation processes. The critical O–O bond formation step in the Kok cycle that is presumed to generate molecular oxygen occurs through the high-valent Mn-oxo species of the water oxidation complex, i.e., the Mn4Ca cluster in photosystem II. Here, we report the spectroscopic characterization of new intermediates during the water oxidation reaction of manganese-based heterogeneous catalysts and assign them as low-spin Mn(IV)-oxo species. Recently, the effects of the spin state in transition metal catalysts on catalytic reactivity have been intensely studied; however, no detailed characterization of a low-spin Mn(IV)-oxo intermediate species currently exists. We demonstrate that a low-spin configuration of Mn(IV), S = 1/2, is stably present in a heterogeneous electrocatalyst of Ni-doped monodisperse 10-nm Mn3O4 nanoparticles via oxo-ligand field engineering. An unprecedented signal (g = 1.83) is found to evolve in the electron paramagnetic resonance spectrum during the stepwise transition from the Jahn–Teller-distorted Mn(III). In-situ Raman analysis directly provides the evidence for Mn(IV)-oxo species as the active intermediate species. Computational analysis confirmed that the substituted nickel species induces the formation of a z-axis-compressed octahedral C4v crystal field that stabilizes the low-spin Mn(IV)-oxo intermediates.

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Section: Results and Discussionmentioning

confidence: 99%

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

et al. 2020

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“…Unlike the chemistry of high‐valent Fe or Mn, studies on nickel‐oxo species do not benefit much from the scarce number of well‐characterized examples of synthetic origin [4g, 12b] . To probe the electronic structure and optical transitions of the yellow intermediate generated from the reaction between 1 and mCPBA, we carried out exploratory DFT and TD‐DFT computational studies.…”

Section: Resultsmentioning

confidence: 99%

Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex

Kim

Jeong

Kim

et al. 2021

Chemistry A European J

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High‐valent metal‐oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox‐active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron‐donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high‐valent nickel species is subsequently formed to carry out oxo‐transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.

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“…[1][2][3][4][5] In these oxidative transformations, Fe(IV)]O species are oen implicated as key oxidizing intermediates. [6][7][8][9][10] Of crucial interest is the effect of the spin state of the Fe IV (O) unit; quintet (S ¼ 2) or triplet (S ¼ 1) ground states might be involved as predicted by density functional theory (DFT) calculations. 11,12 For instance, a high-spin iron(IV)-oxo intermediate was spectroscopically characterized in a-ketoglutarate-dependent taurine dioxygenase (TauD).…”

Section: Introductionmentioning

confidence: 99%

“…14 Inspired by these great achievements in both biological and biomimetic systems, a great number of mononuclear non-haem Fe(IV)]O complexes supported by polydentate ligands have been synthesized and intensively investigated to elucidate their structural, spectroscopic and reactive properties. [6][7][8][9][10][15][16][17][18][19] These Fe(IV)]O complexes exhibit versatile reactivity (for example, enabling alkane hydroxylation) that markedly depends on the use of supporting ligands. 16 In recent years, the Fe(IV)]O complex with a Me 3 NTB (tris(N-methylbenzimidazol-2-yl)methyl)amine) ligand has been demonstrated as the most powerful oxidant among the intermediate-spin (S ¼ 1) iron(IV)-oxo complexes.…”

Section: Introductionmentioning

confidence: 99%

A DFT study on the C–H oxidation reactivity of Fe(iv)–oxo species with N4/N5 ligands derived from l-proline

Lin

Sun

2021

RSC Adv.

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Iron and manganese oxo complexes, oxo wall and beyond

Cited by 202 publications

References 174 publications

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex

A DFT study on the C–H oxidation reactivity of Fe(iv)–oxo species with N4/N5 ligands derived from l-proline

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