title: Reductive elimination of alkylamines from low-valent, alkylpalladium(II) amido complexes.
abstract: A series of three-coordinate norbornylpalladium amido complexes ligated by bulky N-heterocyclic carbene (NHC) ligands were prepared that undergo reductive eliminations to form the alkyl-nitrogen bond of alkylamine products. The rates of reductive elimination reveal that complexes containing more-electron-donating amido groups react faster than those with less-electron-donating amido groups, and complexes containing more-sterically bulky amido groups undergo reductive elimination more slowly than complexes containing less-sterically bulky amido groups. Complexes ligated by more-electron-donating ancillary NHC ligands undergo reductive elimination faster than complexes ligated by less-electron-donating NHC ligands. In contrast to the reductive elimination of benzylamines from bisphosphine-ligated palladium amides, these reactions occur with retention of configuration at the alkyl group, indicating that these reductive eliminations proceed by a concerted pathway. The experimentally determined free energy barrier of 26 kcal/mol is close to the computed free energy barrier of 23.9 kcal/mol (363 K) for a concerted reductive elimination from the isolated, three-coordinate NHC-ligated palladium anilido complex.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Hanley
authors.forename: Seth L
authors.initials: SL
authors.lastname: Marquard
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari
authors.forename: John F
authors.initials: JF
authors.lastname: Hartwig