High-Spin and Low-Spin Perferryl Intermediates in Fe(PDP)-Catalyzed Epoxidations

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High-Spin and Low-Spin Perferryl Intermediates in Fe(PDP)-Catalyzed Epoxidations. / Zima, Alexandra M.; Lyakin, Oleg Y.; Bryliakov, Konstantin P. et al.

In: ChemCatChem, Vol. 11, No. 21, 07.11.2019, p. 5345-5352.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{d3cdce8bcba049b58553cdad73c0fb56,

title = "High-Spin and Low-Spin Perferryl Intermediates in Fe(PDP)-Catalyzed Epoxidations",

abstract = "Two bioinspired hydroxo-bridged diferric complexes 6 and 7 with N4-donor ligands of the PDP type (PDP=N,N′-bis(pyridin-2-ylmethyl)-2,2′-bipyrrolidine), differing by substituents at the pyridine rings (4-NMe2 in 7 vs. 3,5-Me2-4-OMe in 6), efficiently catalyze the enantioselective alkene epoxidation with H2O2 and peracetic acid in the presence of a carboxylic acid additive (up to 99 catalyst turnover numbers, TON, toward epoxide, up to 94 % ee). Catalyst systems based on complex 7 display the high-spin perferryl intermediate 7 aAA (S=3/2, g1, g2=3.69, g3=1.96), whereas catalyst systems based on complex 6 exhibit the low-spin perferryl intermediate 6 aAA (S=1/2, g1=2.07, g2=2.01, g3=1.96). The S=3/2 and the S=1/2 intermediates directly react with cyclohexene and cyclohexane at low temperatures (−40 °C and −85 °C, respectively). The catalyst systems, exhibiting less reactive intermediate 7 aAA, demonstrate higher enantioselectivity (% ee) in the epoxidation of chalcone. The origin of the unprecedented high-spin state of the perferryl intermediate is discussed.",

keywords = "Enzyme models, epoxidation, EPR spectroscopy, iron, reaction mechanisms, OXIDATION, ALKANE HYDROXYLATION, ACTIVE-SITES, REACTIVITY, NONHEME IRON-CATALYSTS, ASYMMETRIC EPOXIDATIONS, COMPOUND I, C-H HYDROXYLATION, ELECTRONIC-STRUCTURE, FE",

author = "Zima, {Alexandra M.} and Lyakin, {Oleg Y.} and Bryliakov, {Konstantin P.} and Talsi, {Evgenii P.}",

year = "2019",

month = nov,

day = "7",

doi = "10.1002/cctc.201900842",

language = "English",

volume = "11",

pages = "5345--5352",

journal = "ChemCatChem",

issn = "1867-3880",

publisher = "Wiley - VCH Verlag GmbH & CO. KGaA",

number = "21",

}

RIS

TY - JOUR

T1 - High-Spin and Low-Spin Perferryl Intermediates in Fe(PDP)-Catalyzed Epoxidations

AU - Zima, Alexandra M.

AU - Lyakin, Oleg Y.

AU - Bryliakov, Konstantin P.

AU - Talsi, Evgenii P.

PY - 2019/11/7

Y1 - 2019/11/7

N2 - Two bioinspired hydroxo-bridged diferric complexes 6 and 7 with N4-donor ligands of the PDP type (PDP=N,N′-bis(pyridin-2-ylmethyl)-2,2′-bipyrrolidine), differing by substituents at the pyridine rings (4-NMe2 in 7 vs. 3,5-Me2-4-OMe in 6), efficiently catalyze the enantioselective alkene epoxidation with H2O2 and peracetic acid in the presence of a carboxylic acid additive (up to 99 catalyst turnover numbers, TON, toward epoxide, up to 94 % ee). Catalyst systems based on complex 7 display the high-spin perferryl intermediate 7 aAA (S=3/2, g1, g2=3.69, g3=1.96), whereas catalyst systems based on complex 6 exhibit the low-spin perferryl intermediate 6 aAA (S=1/2, g1=2.07, g2=2.01, g3=1.96). The S=3/2 and the S=1/2 intermediates directly react with cyclohexene and cyclohexane at low temperatures (−40 °C and −85 °C, respectively). The catalyst systems, exhibiting less reactive intermediate 7 aAA, demonstrate higher enantioselectivity (% ee) in the epoxidation of chalcone. The origin of the unprecedented high-spin state of the perferryl intermediate is discussed.

AB - Two bioinspired hydroxo-bridged diferric complexes 6 and 7 with N4-donor ligands of the PDP type (PDP=N,N′-bis(pyridin-2-ylmethyl)-2,2′-bipyrrolidine), differing by substituents at the pyridine rings (4-NMe2 in 7 vs. 3,5-Me2-4-OMe in 6), efficiently catalyze the enantioselective alkene epoxidation with H2O2 and peracetic acid in the presence of a carboxylic acid additive (up to 99 catalyst turnover numbers, TON, toward epoxide, up to 94 % ee). Catalyst systems based on complex 7 display the high-spin perferryl intermediate 7 aAA (S=3/2, g1, g2=3.69, g3=1.96), whereas catalyst systems based on complex 6 exhibit the low-spin perferryl intermediate 6 aAA (S=1/2, g1=2.07, g2=2.01, g3=1.96). The S=3/2 and the S=1/2 intermediates directly react with cyclohexene and cyclohexane at low temperatures (−40 °C and −85 °C, respectively). The catalyst systems, exhibiting less reactive intermediate 7 aAA, demonstrate higher enantioselectivity (% ee) in the epoxidation of chalcone. The origin of the unprecedented high-spin state of the perferryl intermediate is discussed.

KW - Enzyme models

KW - epoxidation

KW - EPR spectroscopy

KW - iron

KW - reaction mechanisms

KW - OXIDATION

KW - ALKANE HYDROXYLATION

KW - ACTIVE-SITES

KW - REACTIVITY

KW - NONHEME IRON-CATALYSTS

KW - ASYMMETRIC EPOXIDATIONS

KW - COMPOUND I

KW - C-H HYDROXYLATION

KW - ELECTRONIC-STRUCTURE

KW - FE

UR - http://www.scopus.com/inward/record.url?scp=85070323488&partnerID=8YFLogxK

U2 - 10.1002/cctc.201900842

DO - 10.1002/cctc.201900842

M3 - Article

AN - SCOPUS:85070323488

VL - 11

SP - 5345

EP - 5352

JO - ChemCatChem

JF - ChemCatChem

SN - 1867-3880

IS - 21

ER -

ID: 21240785