C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles

William G. Whitehurst; Junho Kim; Stefan G. Koenig; Paul J. Chirik

doi:10.1021/jacs.2c08865

C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles

William G. Whitehurst
, Junho Kim
, Stefan G. Koenig
, Paul J. Chirik

Chemistry

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

18 Scopus citations

Abstract

Five- and six-coordinate cationic bis(phosphine) cobalt(III) metallacycle complexes were synthesized with the general structures, [(depe)Co(cycloneophyl)(L)(L′)][BAr^F₄] (depe = 1,2-bis(diethylphosphino)ethane; cycloneophyl = [κ-C:C-(CH₂C(Me)₂)C₆H₄]; L/L′ = pyridine, pivalonitrile, or the vacant site, BAr₄^F= B[(3,5-(CF₃)₂)C₆H₃]₄). Each of these compounds promoted facile directed C(sp²)-H activation with exclusive selectivity for ortho-alkylated products, consistent with the selectivity of reported cobalt-catalyzed arene-alkene-alkyne coupling reactions. The direct observation of C-H activation by cobalt(III) metallacycles provided experimental support for the intermediacy of these compounds in this class of catalytic C-H functionalization reaction. Deuterium labeling and kinetic studies provided insight into the nature of C-H bond cleavage and C-C bond reductive elimination from isolable cobalt(III) precursors.

Original language	English (US)
Pages (from-to)	19186-19195
Number of pages	10
Journal	Journal of the American Chemical Society
Volume	144
Issue number	41
DOIs	https://doi.org/10.1021/jacs.2c08865
State	Published - Oct 19 2022

All Science Journal Classification (ASJC) codes

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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10.1021/jacs.2c08865

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title = "C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles",

abstract = "Five- and six-coordinate cationic bis(phosphine) cobalt(III) metallacycle complexes were synthesized with the general structures, [(depe)Co(cycloneophyl)(L)(L′)][BArF4] (depe = 1,2-bis(diethylphosphino)ethane; cycloneophyl = [κ-C:C-(CH2C(Me)2)C6H4]; L/L′ = pyridine, pivalonitrile, or the vacant site, BAr4F= B[(3,5-(CF3)2)C6H3]4). Each of these compounds promoted facile directed C(sp2)-H activation with exclusive selectivity for ortho-alkylated products, consistent with the selectivity of reported cobalt-catalyzed arene-alkene-alkyne coupling reactions. The direct observation of C-H activation by cobalt(III) metallacycles provided experimental support for the intermediacy of these compounds in this class of catalytic C-H functionalization reaction. Deuterium labeling and kinetic studies provided insight into the nature of C-H bond cleavage and C-C bond reductive elimination from isolable cobalt(III) precursors.",

author = "Whitehurst, \{William G.\} and Junho Kim and Koenig, \{Stefan G.\} and Chirik, \{Paul J.\}",

year = "2022",

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doi = "10.1021/jacs.2c08865",

language = "English (US)",

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journal = "Journal of the American Chemical Society",

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T1 - C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles

AU - Whitehurst, William G.

AU - Kim, Junho

AU - Koenig, Stefan G.

AU - Chirik, Paul J.

PY - 2022/10/19

Y1 - 2022/10/19

N2 - Five- and six-coordinate cationic bis(phosphine) cobalt(III) metallacycle complexes were synthesized with the general structures, [(depe)Co(cycloneophyl)(L)(L′)][BArF4] (depe = 1,2-bis(diethylphosphino)ethane; cycloneophyl = [κ-C:C-(CH2C(Me)2)C6H4]; L/L′ = pyridine, pivalonitrile, or the vacant site, BAr4F= B[(3,5-(CF3)2)C6H3]4). Each of these compounds promoted facile directed C(sp2)-H activation with exclusive selectivity for ortho-alkylated products, consistent with the selectivity of reported cobalt-catalyzed arene-alkene-alkyne coupling reactions. The direct observation of C-H activation by cobalt(III) metallacycles provided experimental support for the intermediacy of these compounds in this class of catalytic C-H functionalization reaction. Deuterium labeling and kinetic studies provided insight into the nature of C-H bond cleavage and C-C bond reductive elimination from isolable cobalt(III) precursors.

AB - Five- and six-coordinate cationic bis(phosphine) cobalt(III) metallacycle complexes were synthesized with the general structures, [(depe)Co(cycloneophyl)(L)(L′)][BArF4] (depe = 1,2-bis(diethylphosphino)ethane; cycloneophyl = [κ-C:C-(CH2C(Me)2)C6H4]; L/L′ = pyridine, pivalonitrile, or the vacant site, BAr4F= B[(3,5-(CF3)2)C6H3]4). Each of these compounds promoted facile directed C(sp2)-H activation with exclusive selectivity for ortho-alkylated products, consistent with the selectivity of reported cobalt-catalyzed arene-alkene-alkyne coupling reactions. The direct observation of C-H activation by cobalt(III) metallacycles provided experimental support for the intermediacy of these compounds in this class of catalytic C-H functionalization reaction. Deuterium labeling and kinetic studies provided insight into the nature of C-H bond cleavage and C-C bond reductive elimination from isolable cobalt(III) precursors.

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UR - https://www.scopus.com/pages/publications/85139473211#tab=citedBy

U2 - 10.1021/jacs.2c08865

DO - 10.1021/jacs.2c08865

M3 - Article

C2 - 36194198

AN - SCOPUS:85139473211

SN - 0002-7863

VL - 144

SP - 19186

EP - 19195

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 41

ER -

C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles

Abstract

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