Catalytic and stoichiometric oxidation of N,N-dimethylanilines mediated by nonheme oxoiron(IV) complex with tetrapyridyl ligand

Dóra Lakk-Bogáth, Balázs Kripli, Bashdar I. Meena, G. Speier, J. Kaizer

Research output: Contribution to journalArticle

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Abstract

Nonheme iron(II) complex, [(N4Py*)FeII(CH3CN)](ClO4)2 (1) with pentadentate tetrapyridyl ligand (N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine) has been shown to catalyze the oxidation of N,N-dimethylaniline (DMA) with H2O2, tert-butyl hydroperoxide (TBHP), peracetic acid (PAA), meta-chloroperoxybenzoic acid (mCPBA) and PhIO resulting N-methylaniline (MA) as the predominant product with N-methylformanilide (MFA) as a result of a free-radical chain process. The product composition (MA/MFA) is remarkably influenced by the electron density on the substrate, especially in the 1/mCPBA system, and by the co-oxidants used. No formation of MFA occurred when the oxidation of DMA was carried out in the presence of 1 with PhIO as co-oxidants under argon. Based on spectral investigation (UV–Vis) of reaction systems above, oxoiron(IV) intermediate, [FeIV(N4Py*)(O)]2+ (2) has been suggested to be the key active species of the N-dealkylation reaction in all catalytic systems. The shift in the λmax value of the oxoiron(IV) species in the presence of DMA from 705 to 750 nm, and the new intense absorption in the range of 5–600 nm indicates a complexation and charge-transfer (CT) type interactions between the oxidant and substrate. The stoichiometric oxidation of various N,N-dimethylaniline derivatives with 2 provided clear evidence (Hammett correlation with ρ = −1.99, and the large negative slope (−4.1) from the logkobs versus Eo ox (DMAs) plot) for the rate-determining electron transfer (ET) followed by a proton transfer (PT) process.

Original languageEnglish
Pages (from-to)169-175
Number of pages7
JournalPolyhedron
Volume169
DOIs
Publication statusPublished - Sep 1 2019

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Oxidants
Ligands
Oxidation
ligands
oxidation
acids
Acids
Peracetic Acid
tert-Butylhydroperoxide
Proton transfer
Argon
Dynamic mechanical analysis
Substrates
products
Complexation
Free radicals
free radicals
Free Radicals
Carrier concentration
Charge transfer

Keywords

  • Bioinspired oxidation
  • C–H activation
  • Kinetics
  • Nonheme oxoiron complex
  • Oxidative N-dealkylation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Catalytic and stoichiometric oxidation of N,N-dimethylanilines mediated by nonheme oxoiron(IV) complex with tetrapyridyl ligand. / Lakk-Bogáth, Dóra; Kripli, Balázs; Meena, Bashdar I.; Speier, G.; Kaizer, J.

In: Polyhedron, Vol. 169, 01.09.2019, p. 169-175.

Research output: Contribution to journalArticle

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AU - Lakk-Bogáth, Dóra

AU - Kripli, Balázs

AU - Meena, Bashdar I.

AU - Speier, G.

AU - Kaizer, J.

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N2 - Nonheme iron(II) complex, [(N4Py*)FeII(CH3CN)](ClO4)2 (1) with pentadentate tetrapyridyl ligand (N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine) has been shown to catalyze the oxidation of N,N-dimethylaniline (DMA) with H2O2, tert-butyl hydroperoxide (TBHP), peracetic acid (PAA), meta-chloroperoxybenzoic acid (mCPBA) and PhIO resulting N-methylaniline (MA) as the predominant product with N-methylformanilide (MFA) as a result of a free-radical chain process. The product composition (MA/MFA) is remarkably influenced by the electron density on the substrate, especially in the 1/mCPBA system, and by the co-oxidants used. No formation of MFA occurred when the oxidation of DMA was carried out in the presence of 1 with PhIO as co-oxidants under argon. Based on spectral investigation (UV–Vis) of reaction systems above, oxoiron(IV) intermediate, [FeIV(N4Py*)(O)]2+ (2) has been suggested to be the key active species of the N-dealkylation reaction in all catalytic systems. The shift in the λmax value of the oxoiron(IV) species in the presence of DMA from 705 to 750 nm, and the new intense absorption in the range of 5–600 nm indicates a complexation and charge-transfer (CT) type interactions between the oxidant and substrate. The stoichiometric oxidation of various N,N-dimethylaniline derivatives with 2 provided clear evidence (Hammett correlation with ρ = −1.99, and the large negative slope (−4.1) from the logkobs versus Eo ox (DMAs) plot) for the rate-determining electron transfer (ET) followed by a proton transfer (PT) process.

AB - Nonheme iron(II) complex, [(N4Py*)FeII(CH3CN)](ClO4)2 (1) with pentadentate tetrapyridyl ligand (N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine) has been shown to catalyze the oxidation of N,N-dimethylaniline (DMA) with H2O2, tert-butyl hydroperoxide (TBHP), peracetic acid (PAA), meta-chloroperoxybenzoic acid (mCPBA) and PhIO resulting N-methylaniline (MA) as the predominant product with N-methylformanilide (MFA) as a result of a free-radical chain process. The product composition (MA/MFA) is remarkably influenced by the electron density on the substrate, especially in the 1/mCPBA system, and by the co-oxidants used. No formation of MFA occurred when the oxidation of DMA was carried out in the presence of 1 with PhIO as co-oxidants under argon. Based on spectral investigation (UV–Vis) of reaction systems above, oxoiron(IV) intermediate, [FeIV(N4Py*)(O)]2+ (2) has been suggested to be the key active species of the N-dealkylation reaction in all catalytic systems. The shift in the λmax value of the oxoiron(IV) species in the presence of DMA from 705 to 750 nm, and the new intense absorption in the range of 5–600 nm indicates a complexation and charge-transfer (CT) type interactions between the oxidant and substrate. The stoichiometric oxidation of various N,N-dimethylaniline derivatives with 2 provided clear evidence (Hammett correlation with ρ = −1.99, and the large negative slope (−4.1) from the logkobs versus Eo ox (DMAs) plot) for the rate-determining electron transfer (ET) followed by a proton transfer (PT) process.

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KW - C–H activation

KW - Kinetics

KW - Nonheme oxoiron complex

KW - Oxidative N-dealkylation

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