Density Functional Theory Investigation of the Alkyl-Alkyl Negishi Cross-Coupling Reaction Catalyzed by N-Heterocyclic Carbene (NHC)-Pd Complexes

Autor:	Eric Assen B. Kantchev, Alan C. Hopkinson, De Cai Fang, Imre G. Csizmadia, Gregory A. Chass, Niloufar Hadei, Christopher J. O'Brien, Michael G. Organ, Wei Hua Mu
Rok vydání:	2009
Předmět:	Transmetalation Coordination sphere Chemistry Ligand Stereochemistry Negishi coupling Organic Chemistry General Chemistry Oxidative addition Catalysis Coupling reaction Reductive elimination Stille reaction
Zdroj:	Chemistry - A European Journal. 15:4281-4288
ISSN:	1521-3765 0947-6539
DOI:	10.1002/chem.200900042
Popis:	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.
Databáze:	OpenAIRE
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