The reductive elimination of 2-hydrocarbyl-imidazolium salts from hydrocarbyl-palladium complexes bearing N-heterocyclic carbene (NHC) ligands represents an important deactivation route for catalysts of this type. We have explored the influence that carbene N-substituents have on both the activation energy and the overall thermodynamics of the reductive elimination reaction using density functional theory (DFT). Given the proximity of the N-substituent to the three-centred transition structure, steric bulk has little influence on the activation barrier and it is electronic factors that dominate the barriers' magnitude. Increased electron donation from the departing NHC ligand acts to stabilise the associated complex against reductive elimination, with stability following the trend: Cl < H < Ph < Me < Cy < iPr < neopentyl < tBu. The intimate involvement of the carbene pπ-orbital in determining the barrier to reductive elimination means N-substituents that are capable of removing π-density (e.g. phenyl) act to promote a more facile reductive elimination. © The Royal Society of Chemistry 2006.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Other Chemical Sciences
Research Field:	Organometallic Chemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Graham, DC (Dr David Graham)
Author:	Cavell, KJ (Professor Kingsley Cavell)
Author:	Yates, BF (Professor Brian Yates)
ID Code:	43154
Year Published:	2006
Web of Science® Times Cited:	48
Deposited By:	Chemistry
Deposited On:	2006-08-01
Last Modified:	2012-03-05
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