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Nickel(II) Complexes of Bidentate N‐Heterocyclic Carbene/Phosphine Ligands: Efficient Catalysts for Suzuki Coupling of Aryl Chlorides
Author(s) -
Lee ChunChin,
Ke WeiChi,
Chan KaiTing,
Lai ChunLiang,
Hu ChingHan,
Lee Hon Man
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600502
Subject(s) - aryl , carbene , chemistry , nickel , ligand (biochemistry) , denticity , phosphine , phenylboronic acid , catalysis , palladium , medicinal chemistry , polymer chemistry , organic chemistry , crystal structure , alkyl , biochemistry , receptor
Nickel(II) complexes of bidentate N‐heterocyclic carbene (NHC)/phosphane ligand L were prepared and structurally characterized. Unlike palladium, which forms [PdCl 2 (L)], the stable nickel product isolated is the ionic [Ni(L) 2 ]Cl 2 . These Ni II complexes are highly robust in air. Among different N‐substituents on the ligand framework, the nickel complex of ligand L bearing N ‐1‐naphthylmethyl groups ( 2 a ) is a highly effective catalyst for Suzuki cross‐coupling between phenylboronic acid and a range of aryl halides, including unreactive aryl chlorides. The activities of 2 a are largely superior to those of other reported nickel NHC complexes and their palladium counterparts. Unlike the previously reported [NiCl 2 (dppe)] (dppe=1,2‐bis(diphenylphosphino)ethane), 2 a can effectively catalyze the cross‐coupling reaction without the need for a catalytic amount of PPh 3 , and this suggests that the PPh 2 functionality of hybrid NHC ligand L can partially take on the role of free PPh 3 . However, for unreactive aryl chlorides at low catalyst loading, the presence of PPh 3 accelerates the reaction.