摘要
We present the mechanistic understanding of an electrochemically-driven nickel-catalyzed coupling reaction.Computational analysis reveals that the spin density is mostly residing on the nickel(Ni)center when Ni^(II) is reduced to NiI.Ni-mediated halogen atom abstraction through outer-sphere electron-transfer pathway to yield coupling products under mild conditions is demonstrated.Importantly,we have elucidated the role of Ni^(I) and Ni^(0) for successive coupling of benzyl bromide and benzyl chloride derivatives,respectively,to corresponding bibenzyl products.The Ni-catalyst bearing a PN^(3) P-ligand is an effective catalyst,producing a strong ligand effect on the reactivity and selectivity for the homocoupling reactions.
