Electrophilic C-H activation at {Cp*Ir}: Ancillary-ligand control of the mechanism of C-H activation

David L. Davies, S. M A Donald, Omar Al-Duaij, Stuart A. Macgregor, Manuel Pölleth

Research output: Contribution to journalArticle

Abstract

Density functional calculations on the low-temperature cyclometalation of dimethylbenzylamine with [IrCl2Cp*]2/NaOAc have characterized a novel electrophilic activation pathway for C-H bond activation. C-H activation occurs from [Ir(DMBA-H)(k2-OAc)Cp*]+, and OAc plays a central role in determining the barrier for reaction. Dissociation of the proximal OAc arm sets up a facile intramolecular deprotonation via a geometrically convenient six-membered transition state. Dissociation of the distal OAc arm, however, leads to a higher energy four-membered (s-bond metathesis) transition state, while oxidative addition is even higher in energy. For this Ir3+ system, these three mechanisms appear to lie within a continuum in which the participation of the metal center and an H-accepting ancillary ligand are inversely related. The ability of the ancillary ligand to act as a proton acceptor is the key factor in determining which mechanism pertains. Copyright © 2006 American Chemical Society.

Original languageEnglish
Pages (from-to)4210-4211
Number of pages2
JournalJournal of the American Chemical Society
Volume128
Issue number13
DOIs
Publication statusPublished - 5 Apr 2006

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Chemical activation
Ligands
9,10-Dimethyl-1,2-benzanthracene
Deprotonation
Density functional theory
Protons
Metals
Temperature

Cite this

Davies, David L. ; Donald, S. M A ; Al-Duaij, Omar ; Macgregor, Stuart A. ; Pölleth, Manuel. / Electrophilic C-H activation at {Cp*Ir} : Ancillary-ligand control of the mechanism of C-H activation. In: Journal of the American Chemical Society. 2006 ; Vol. 128, No. 13. pp. 4210-4211.
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abstract = "Density functional calculations on the low-temperature cyclometalation of dimethylbenzylamine with [IrCl2Cp*]2/NaOAc have characterized a novel electrophilic activation pathway for C-H bond activation. C-H activation occurs from [Ir(DMBA-H)(k2-OAc)Cp*]+, and OAc plays a central role in determining the barrier for reaction. Dissociation of the proximal OAc arm sets up a facile intramolecular deprotonation via a geometrically convenient six-membered transition state. Dissociation of the distal OAc arm, however, leads to a higher energy four-membered (s-bond metathesis) transition state, while oxidative addition is even higher in energy. For this Ir3+ system, these three mechanisms appear to lie within a continuum in which the participation of the metal center and an H-accepting ancillary ligand are inversely related. The ability of the ancillary ligand to act as a proton acceptor is the key factor in determining which mechanism pertains. Copyright {\circledC} 2006 American Chemical Society.",
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Electrophilic C-H activation at {Cp*Ir} : Ancillary-ligand control of the mechanism of C-H activation. / Davies, David L.; Donald, S. M A; Al-Duaij, Omar; Macgregor, Stuart A.; Pölleth, Manuel.

In: Journal of the American Chemical Society, Vol. 128, No. 13, 05.04.2006, p. 4210-4211.

Research output: Contribution to journalArticle

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