Nickel(II) complexes of amine functionalized N-heterocyclic carbenes (NHCs), synthesis and catalysis in Kumada coupling of aryl chlorides

A new amine functionalized double chelate NHC nickel complex 2 was synthesized and characterized. Complexes 4a and 4b were generated through an improved synthetic method. Catalytic ability of the three nickel complexes were tested in Kumada coupling reaction. Complex 2 showed the best catalytic activity among them. With only 0.5 mol% of complex 2, the coupling of aryl chlorides with Grignard reagents received good yields.