TY - JOUR
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.
N1 - Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
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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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 -