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

Christina Wegeberg, Frants R. Lauritsen, Cathrine Frandsen, Steen Mørup, Wesley R. Browne, Christine J. Mckenzie*

*Corresponding author for this work

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Abstract

The reactivity of [FeIII(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 H2O2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1)catalysed H2O2 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)FeIIIO-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 FeIII/FeII redox potentials for the pro-catalysts.
Original languageEnglish
JournalChemistry: A European Journal
Volume24
Issue number20
Pages (from-to)5134-5145
ISSN0947-6539
DOIs
Publication statusPublished - 2018

Cite this

Wegeberg, Christina ; Lauritsen, Frants R. ; Frandsen, Cathrine ; Mørup, Steen ; Browne, Wesley R. ; Mckenzie, Christine J. / Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway. In: Chemistry: A European Journal. 2018 ; Vol. 24, No. 20. pp. 5134-5145.
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title = "Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway",
abstract = "The reactivity of [FeIII(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 H2O2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1)catalysed H2O2 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)FeIIIO-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 {\"I}ƒ-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 FeIII/FeII redox potentials for the pro-catalysts.",
author = "Christina Wegeberg and Lauritsen, {Frants R.} and Cathrine Frandsen and Steen M{\o}rup and Browne, {Wesley R.} and Mckenzie, {Christine J.}",
year = "2018",
doi = "10.1002/chem.201704615",
language = "English",
volume = "24",
pages = "5134--5145",
journal = "Chemistry: A European Journal",
issn = "0947-6539",
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Directing a Non-Heme Iron(III)-Hydroperoxide Species on a Trifurcated Reactivity Pathway. / Wegeberg, Christina; Lauritsen, Frants R.; Frandsen, Cathrine; Mørup, Steen; Browne, Wesley R.; Mckenzie, Christine J.

In: Chemistry: A European Journal, Vol. 24, No. 20, 2018, p. 5134-5145.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

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

AU - Wegeberg, Christina

AU - Lauritsen, Frants R.

AU - Frandsen, Cathrine

AU - Mørup, Steen

AU - Browne, Wesley R.

AU - Mckenzie, Christine J.

PY - 2018

Y1 - 2018

N2 - The reactivity of [FeIII(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 H2O2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1)catalysed H2O2 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)FeIIIO-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 FeIII/FeII redox potentials for the pro-catalysts.

AB - The reactivity of [FeIII(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 H2O2 and presence or absence of sacrificial substrates. The outcome can be switched between: 1)catalysed H2O2 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)FeIIIO-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 FeIII/FeII redox potentials for the pro-catalysts.

U2 - 10.1002/chem.201704615

DO - 10.1002/chem.201704615

M3 - Journal article

C2 - 29086452

VL - 24

SP - 5134

EP - 5145

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

SN - 0947-6539

IS - 20

ER -