Bimetallic Oxidative Addition in Nickel-Catalyzed Alkyl-Aryl Kumada Coupling Reactions

The mechanism of alkylaryl Kumada coupling catalyzed by the nickel pincer complex Nickamine was studied. Experiments using radical-probe substrates and DFT calculations established a bimetallic oxidative addition mechanism. Kinetic measurements showed that transmetalation rather than oxidative addition was the turnover-determining step. The transmetalation involved a bimetallic pathway.