title: Density functional theory investigation of the alkyl-alkyl Negishi cross-coupling reaction catalyzed by N-heterocyclic carbene (NHC)-Pd complexes.
abstract: A novel mechanism is proposed for the Pd-1,3-(2,6-diisopropylphenyl)imidazolyl-2-ylidene (1) catalyzed Negishi reaction. DFT computations supported by atoms-in-molecules (AIM) analyses of non-truncated models show that a "steric wall" created by the N-substituent on the ligand guides reactants to and from the Pd center. Notably, transmetalation and not oxidative addition is found to be rate-limiting. Additionally, a key Pd-Zn interaction (approximately = 2.4 A, rho(b) approximately = 0.0600 au) is identified in the mechanism. This interaction persists beyond reductive elimination and, in combination with the ligand, facilitates reductive elimination by creating a highly sterically crowded environment in the coordination sphere of the Pd center.
authors.affiliation: School of Chemistry, University of Wales, Bangor, LL57 2UW, UK. gchass@giocomms.org
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Chass
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: O'Brien
authors.forename: Niloufar
authors.initials: N
authors.lastname: Hadei
authors.forename: Eric Assen B
authors.initials: EA
authors.lastname: Kantchev
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Mu
authors.forename: De-Cai
authors.initials: DC
authors.lastname: Fang
authors.forename: Alan C
authors.initials: AC
authors.lastname: Hopkinson
authors.forename: Imre G
authors.initials: IG
authors.lastname: Csizmadia
authors.forename: Michael G
authors.initials: MG
authors.lastname: Organ