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The influence of N-substitution on the reductive elimination behaviour of hydrocarbyl-palladium-carbene complexes-a DFT study

journal contribution
posted on 2023-05-16, 18:50 authored by Graham, DC, Cavell, KJ, Brian YatesBrian Yates
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.

History

Publication title

Dalton Transactions

Volume

6

Issue

14

Pagination

1768-1775

ISSN

1477-9226

Department/School

School of Natural Sciences

Publisher

Royal Chemical Society

Place of publication

Cambridge UK

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

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