Nickel(ii) complexes containing tridentate ONCi ligands (i = abnormal N-heterocyclic carbene donors) and their catalytic application in Suzuki-Miyaura coupling reaction

New nickel complexes with tridentate phenoxy-amidate-aNHC donor groups were synthesized from the reactions between nickel acetate and imidazolium ligand precursors in net pyridine. An unusual degradation pathway was observed, leading to imidazole derivatives occupying the fourth coordination sites in these square planar complexes. A new imidazole-coordinated nickel complex was found to be efficient in catalyzing Suzuki-Miyaura cross-coupling with aryl chlorides under 3 mol% of catalyst loading. The catalytic activities were superior to those of its reported normal NHC counterpart. Instead of the common procedure of using additional phosphine, the addition of IMes center dot HCl significantly enhances the product yields of the catalytic reaction.

Automated summary

New nickel complexes with tridentate phenoxy-amidate-aNHC donor groups were synthesized and showed superior catalytic activities compared to the reported normal NHC counterparts. The addition of IMes center dot HCl significantly enhanced the product yields of the catalytic reaction.