OO Bond Formation Mediated by a Hexanuclear Iron Complex Supported on a Stannoxane Core

Kundu, Subrata; Matito, Eduard; Walleck, Stephan; Pfaff, Florian Felix; Heims, Florian; Rábay, Battist; Luis, Josep M.; Braun, Beatrice; Glaser, Thorsten; Ray, Kallol

doi:10.1002/chem.201102326

Cited by 44 publications

(34 citation statements)

References 36 publications

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“…2b). This value is comparable to those recorded for metal-superoxo complexes 9, 13, 20, 21 , suggesting that the O 2 unit in 1 possesses superoxo character.…”

Section: Resultssupporting

confidence: 82%

“…Moreover, reactivities of synthetic nonheme iron(III)-superoxo complexes in electrophilic and nucleophilic oxidation reactions have been rarely reported in biomimetic studies. 20 We therefore performed these reactions with the isolated, well-characterized nonheme iron(III)-superoxo complex, 1 . First, the reactivity of 1 was examined in the oxidation of C-H and O-H bonds, with precedents that metal-superoxo species are potent oxidants in the C-H and O-H substrate oxygenation reactions 11, 26–28 .…”

Section: Resultsmentioning

confidence: 99%

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Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex

et al. 2014

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Mononuclear nonheme iron(III)-superoxo species (FeIII-O2−•) have been implicated as key intermediates in the catalytic cycles of dioxygen activation by nonheme iron enzymes. Although nonheme iron(III)-superoxo species have been trapped and characterized spectroscopically in enzymatic and biomimetic reactions, no structural information has yet been obtained. Here we report for the first time the isolation, spectroscopic characterization, and crystal structure of a mononuclear side-on (η2) iron(III)-superoxo complex with a tetraamido macrocyclic ligand (TAML), [FeIII (TAML) (O2)]2− (1). The nonheme iron(III)-superoxo species undergoes both electrophilic and nucleophilic oxidation reactions as well as O2-transfer between metal complexes. In the O2-transfer reaction, 1 transfers the bound O2 unit to a manganese(III) analogue, resulting in the formation of a manganese(IV)-peroxo complex, [MnIV(TAML)(O2)]2− (2); 2 is characterized structurally and spectroscopically as a mononuclear side-on (η2) manganese(IV)-peroxo complex. The difference in the redox distribution between the metal ions and O2 in 1 and 2 is rationalized using density functional theory calculations.

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“…2b). This value is comparable to those recorded for metal-superoxo complexes 9, 13, 20, 21 , suggesting that the O 2 unit in 1 possesses superoxo character.…”

Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex

et al. 2014

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“…7 are postulated two possible mechanism an oxo/oxyl radical coupling mechanism to form the O–O bond (Path a , Fig. 7) 12 and the alternative hypothesis entailing electron transfer from Fe IV to Ce IV to generate a highly electrophilic {Fe V (O)(μ-O)Ce III } oxidant (Fig. 7, path b ).…”

Section: Discussionmentioning

confidence: 99%

“…The reaction is particularly appealing because it has been recognized as one of the bottleneck challenges for the success of artificial photosynthesis, and the identification of iron compounds as efficient catalysts opens novel directions in the quest for earth-abundant systems that could be used on a large scale 8–11 . In this context, the study of the water oxidation (WO) reaction with chemical oxidants catalysed by well-defined coordination complexes can clarify fundamental principles underlying the mechanisms of O-O bond formation and cleavage 12,13 , the latter being at the heart of chemical processes by which aerobic organisms respire 14 . Most remarkably, given the strong parallels between the oxidation chemistry of iron and manganese compounds 15 , it can be envisioned that fundamental chemical insights extracted from studies of O-O bond formation by iron coordination compounds can shed light on intermediates and mechanisms operating at the Oxygen Evolving Complex (OEC).…”

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confidence: 99%

Evidence for an oxygen evolving iron–oxo–cerium intermediate in iron-catalysed water oxidation

et al. 2015

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The non-haem iron complex α-[FeII(CF3SO3)2(mcp)] (mcp = (N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-1,2-cis-diaminocyclohexane) reacts with CeIV to oxidize water to O2, representing an iron-based functional model for the oxygen evolving complex of photosystem II. Here we trap an intermediate, characterized by cryospray ionization high resolution mass spectrometry and resonance Raman spectroscopy, and formulated as [(mcp)FeIV(O) (μ-O)CeIV(NO3)3]+, the first example of a well-characterized inner-sphere complex to be formed in cerium(IV)-mediated water oxidation. The identification of this reactive FeIV–O–CeIV adduct may open new pathways to validate mechanistic notions of an analogous MnV–O–CaII unit in the oxygen evolving complex that is responsible for carrying out the key O–O bond forming step.

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“…[3] To date,afew mononuclear non-heme iron(III)superoxo species have been characterized in some enzymes and synthetic model systems. [5][6][7][8][9][10] As reported herein, we have successfully characterized am ononuclear iron(III)-superoxo complex with azole-based ligands. [5][6][7][8][9][10] As reported herein, we have successfully characterized am ononuclear iron(III)-superoxo complex with azole-based ligands.…”

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confidence: 99%

Characterization of Mononuclear Non‐heme Iron(III)‐Superoxo Complex with a Five‐Azole Ligand Set

et al. 2015

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Reaction of O 2 with ah igh-spin mononuclear iron(II) complex supported by af ive-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species,w hich was characterized by UV/Vis spectroscopya nd resonance Raman spectroscopy.1 HNMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with Hatom donating reagents to give al ow-spin iron(III)-hydroperoxo species showing characteristic UV/Vis,r esonance Raman, and EPR spectra.

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OO Bond Formation Mediated by a Hexanuclear Iron Complex Supported on a Stannoxane Core

Cited by 44 publications

References 36 publications

Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex

Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex

Evidence for an oxygen evolving iron–oxo–cerium intermediate in iron-catalysed water oxidation

Characterization of Mononuclear Non‐heme Iron(III)‐Superoxo Complex with a Five‐Azole Ligand Set

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