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Autocatalysis for C-H bond activation by ruthenium(II) complexes in catalytic arylation of functional arenes.

Abstract : Kinetic data for the C-H bond activation of 2-phenylpyridine by Ru(II)(carboxylate)(2)(p-cymene) I (acetate) and I' (pivalate) are available for the first time. They reveal an irreversible autocatalytic process catalyzed by the coproduct HOAc or HOPiv (acetonitrile, 27 °C). The overall reaction is indeed accelerated by the carboxylic acid coproduct and water. It is retarded by a base, in agreement with an autocatalytic process induced by HOAc or HOPiv that favors the dissociation of one carboxylate ligand from I and I' and consequently the ensuing complexation of 2-phenylpyridine (2-PhPy). The C-H bond activation initially delivers Ru(O(2)CR)(o-C(6)H(4)-Py)(p-cymene) A or A', containing one carboxylate ligand (OAc or OPiv, respectively). The overall reaction is accelerated by added acetates. Consequently, C-H bond activation (faster for acetate I than for pivalate I') proceeds via an intermolecular deprotonation of the C-H bond of the ligated 2-PhPy by the acetate or pivalate anion released from I or I', respectively. The 18e complexes A and A' easily dissociate, by displacement of the carboxylate by the solvent (also favored by the carboxylic acid), to give the same cationic complex B(+) {[Ru(o-C(6)H(4)-Py)(p-cymene)(MeCN)](+)}. Complex B(+) is reactive toward oxidative addition of phenyl iodide, leading to the diphenylated 2-pyridylbenzene.
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https://hal.archives-ouvertes.fr/hal-00651994
Contributor : Françoise Toupet Connect in order to contact the contributor
Submitted on : Wednesday, December 14, 2011 - 4:31:55 PM
Last modification on : Friday, October 15, 2021 - 1:39:45 PM

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Emmanuel Ferrer Flegeau, Christian Bruneau, Pierre Dixneuf, Anny Jutand. Autocatalysis for C-H bond activation by ruthenium(II) complexes in catalytic arylation of functional arenes.. Journal of the American Chemical Society, American Chemical Society, 2011, 133 (26), pp.10161-70. ⟨10.1021/ja201462n⟩. ⟨hal-00651994⟩

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