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 NiII 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 NiI and Ni0 for successive coupling of benzyl bromide and benzyl chloride derivatives, respectively, to corresponding bibenzyl products. The Ni-catalyst bearing a PN3 P-ligand is an effective catalyst, producing a strong ligand effect on the reactivity and selectivity for the homocoupling reactions.

中文翻译：

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机械阐明金属氧化态在镍介导的苄基卤化物电催化偶联中的作用

我们介绍了电化学驱动的镍催化的偶联反应的机理理解。计算分析表明，当NiII还原为NiI时，自旋密度主要位于镍（Ni）中心。镍介导的卤素原子通过外球电子转移途径的提取在温和条件下产生偶联产物。重要的是，我们阐明了NiI和Ni0在分别将苄基溴和苄基氯衍生物连续偶联到相应的联苄产物上的作用。带有PN3 P-配体的Ni催化剂是有效的催化剂，对均偶联反应的反应性和选择性产生强大的配体作用。