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Donor-Functionalized Heterocyclic Carbene Complexes of Palladium (II): Efficient Catalysts for C-C Coupling Reactions
journal contribution
posted on 2023-05-16, 12:20 authored by McGuinness, DS, Cavell, KJPd II complexes of donor-functionalized heterocyclic carbene ligands have been synthesized through a route involving carbene transfer from Ag I carbene precursors. The Ag complexes undergo facile reaction with PdCl 2(MeCN) 2 to yield Pd(C∧OPh) 2Cl 2 (3a), Pd(C∧OOMe) 2Cl 2 (3b), and Pd(C∧N) 2Cl 2 (3c) (C∧OPh = 3-methyl-1-phenacylimidazolin-2-ylidene, C∧OOMe = 3-methyl-1-(methylacetyl)imidazolin-2-ylidene, C∧N = 3-methyl-1-picolylimidazolin-2-ylidene), from which [Pd(C∧OOMe) 2(MeCN) 2][BF 4] 2 (4b) and [Pd(C∧N) 2][BF 4] 2 (4c) can be prepared by halide abstraction. When PdMeCl(cod) (cod = cyclooctadiene) is treated with the Ag complexes 2b and 2c, the Me-Pd carbene complexes [PdMe(C∧OOMe)Cl] 2 (5b), PdMe-(C∧N)Cl (5c), PdMe(C∧OOMe) 2Cl (6b), and PdMe(C∧N) 2Cl (6c) are obtained. The C∧OPh and CAOOMe ligands are monodentate with a dangling functional moiety in all complexes, while the CAN ligand exhibits both monodentate and chelating behavior. Several complexes give rise to highly active and very stable catalysts for Heck, Suzuki, and Sonogashira coupling reactions, with turnover numbers of up to 1 700 000 (Heck) and 127 500 (Suzuki) being obtained.
History
Publication title
OrganometallicsVolume
19Issue
5Pagination
741-748ISSN
0276-7333Department/School
School of Natural SciencesPublisher
American Chemical SocietyPlace of publication
USARepository Status
- Restricted