Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway

Christina Wegeberg, Frants Roager Lauritsen, Cathrine Frandsen, Steen Mørup, Wesley R. Browne, Christine McKenzie*

*Kontaktforfatter for dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

The reactivity of [Fe III(tpena)] 2+ (tpena=N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate) as a catalyst for oxidation reactions depends on its ratio to the terminal oxidant H 2O 2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1) catalysed H 2O 2 disproportionation, 2) selective catalytic oxidation of methanol or benzyl alcohol to the corresponding aldehyde, or 3) oxidative decomposition of the tpena ligand. A common mechanism is proposed involving homolytic O−O cleavage in the detected transient purple low-spin (S=1/2) [(tpenaH)Fe IIIO−OH] 2+. The resultant iron(IV) oxo and hydroxyl radical both participate in controllable hydrogen-atom transfer (HAT) reactions. Consistent with the presence of a weaker σ-donor carboxylate ligand, the most pronounced difference in the spectroscopic properties of [Fe(OOH)(tpenaH)] 2+ and its conjugate base, [Fe(OO)(tpenaH)] +, compared to non-heme iron(III) peroxide analogues supported by neutral multidentate N-only ligands, are slightly blue-shifted maxima of the visible absorption band assigned to ligand-to-metal charge-transfer (LMCT) transitions and, corroborating this, lower Fe III/Fe II redox potentials for the pro-catalysts.

OriginalsprogEngelsk
TidsskriftChemistry: A European Journal
Vol/bind24
Udgave nummer20
Sider (fra-til)5134-5145
ISSN0947-6539
DOI
StatusUdgivet - 2018

Fingeraftryk

Ligands
Iron
Catalysts
Catalytic oxidation
Peroxides
Aldehydes
Oxidants
Charge transfer
Absorption spectra
Methanol
Alcohols
Decomposition
Atoms
Oxidation
Hydrogen
Substrates
Metals

Citer dette

Wegeberg, Christina ; Lauritsen, Frants Roager ; Frandsen, Cathrine ; Mørup, Steen ; Browne, Wesley R. ; McKenzie, Christine. / Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway. I: Chemistry: A European Journal. 2018 ; Bind 24, Nr. 20. s. 5134-5145.
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title = "Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway",
abstract = "The reactivity of [Fe III(tpena)] 2+ (tpena=N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate) as a catalyst for oxidation reactions depends on its ratio to the terminal oxidant H 2O 2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1) catalysed H 2O 2 disproportionation, 2) selective catalytic oxidation of methanol or benzyl alcohol to the corresponding aldehyde, or 3) oxidative decomposition of the tpena ligand. A common mechanism is proposed involving homolytic O−O cleavage in the detected transient purple low-spin (S=1/2) [(tpenaH)Fe IIIO−OH] 2+. The resultant iron(IV) oxo and hydroxyl radical both participate in controllable hydrogen-atom transfer (HAT) reactions. Consistent with the presence of a weaker σ-donor carboxylate ligand, the most pronounced difference in the spectroscopic properties of [Fe(OOH)(tpenaH)] 2+ and its conjugate base, [Fe(OO)(tpenaH)] +, compared to non-heme iron(III) peroxide analogues supported by neutral multidentate N-only ligands, are slightly blue-shifted maxima of the visible absorption band assigned to ligand-to-metal charge-transfer (LMCT) transitions and, corroborating this, lower Fe III/Fe II redox potentials for the pro-catalysts.",
keywords = "H O activation, N,O ligands, high-valent iron, hydroxyl radical, iron(IV), peroxides",
author = "Christina Wegeberg and Lauritsen, {Frants Roager} and Cathrine Frandsen and Steen M{\o}rup and Browne, {Wesley R.} and Christine McKenzie",
year = "2018",
doi = "10.1002/chem.201704615",
language = "English",
volume = "24",
pages = "5134--5145",
journal = "Chemistry: A European Journal",
issn = "0947-6539",
publisher = "Wiley - V C H Verlag GmbH & Co. KGaA",
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Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway. / Wegeberg, Christina ; Lauritsen, Frants Roager ; Frandsen, Cathrine; Mørup, Steen; Browne, Wesley R.; McKenzie, Christine.

I: Chemistry: A European Journal, Bind 24, Nr. 20, 2018, s. 5134-5145.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway

AU - Wegeberg, Christina

AU - Lauritsen, Frants Roager

AU - Frandsen, Cathrine

AU - Mørup, Steen

AU - Browne, Wesley R.

AU - McKenzie, Christine

PY - 2018

Y1 - 2018

N2 - The reactivity of [Fe III(tpena)] 2+ (tpena=N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate) as a catalyst for oxidation reactions depends on its ratio to the terminal oxidant H 2O 2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1) catalysed H 2O 2 disproportionation, 2) selective catalytic oxidation of methanol or benzyl alcohol to the corresponding aldehyde, or 3) oxidative decomposition of the tpena ligand. A common mechanism is proposed involving homolytic O−O cleavage in the detected transient purple low-spin (S=1/2) [(tpenaH)Fe IIIO−OH] 2+. The resultant iron(IV) oxo and hydroxyl radical both participate in controllable hydrogen-atom transfer (HAT) reactions. Consistent with the presence of a weaker σ-donor carboxylate ligand, the most pronounced difference in the spectroscopic properties of [Fe(OOH)(tpenaH)] 2+ and its conjugate base, [Fe(OO)(tpenaH)] +, compared to non-heme iron(III) peroxide analogues supported by neutral multidentate N-only ligands, are slightly blue-shifted maxima of the visible absorption band assigned to ligand-to-metal charge-transfer (LMCT) transitions and, corroborating this, lower Fe III/Fe II redox potentials for the pro-catalysts.

AB - The reactivity of [Fe III(tpena)] 2+ (tpena=N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate) as a catalyst for oxidation reactions depends on its ratio to the terminal oxidant H 2O 2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1) catalysed H 2O 2 disproportionation, 2) selective catalytic oxidation of methanol or benzyl alcohol to the corresponding aldehyde, or 3) oxidative decomposition of the tpena ligand. A common mechanism is proposed involving homolytic O−O cleavage in the detected transient purple low-spin (S=1/2) [(tpenaH)Fe IIIO−OH] 2+. The resultant iron(IV) oxo and hydroxyl radical both participate in controllable hydrogen-atom transfer (HAT) reactions. Consistent with the presence of a weaker σ-donor carboxylate ligand, the most pronounced difference in the spectroscopic properties of [Fe(OOH)(tpenaH)] 2+ and its conjugate base, [Fe(OO)(tpenaH)] +, compared to non-heme iron(III) peroxide analogues supported by neutral multidentate N-only ligands, are slightly blue-shifted maxima of the visible absorption band assigned to ligand-to-metal charge-transfer (LMCT) transitions and, corroborating this, lower Fe III/Fe II redox potentials for the pro-catalysts.

KW - H O activation

KW - N,O ligands

KW - high-valent iron

KW - hydroxyl radical

KW - iron(IV)

KW - peroxides

U2 - 10.1002/chem.201704615

DO - 10.1002/chem.201704615

M3 - Journal article

VL - 24

SP - 5134

EP - 5145

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

SN - 0947-6539

IS - 20

ER -