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

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 (σ-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.

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


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