Zinc and manganese are widely used as reductants in synthetic methods, such as nickel-catalysed cross-electrophile coupling (XEC) reactions, but their redox potentials are unknown in organic solvents. Here we show how open-circuit potential measurements may be used to determine the thermodynamic potentials of Zn and Mn in different organic solvents and in the presence of common reaction additives. The impact of these Zn and Mn potentials is analysed for a pair of Ni-catalysed reactions, each showing a preference for one of the two reductants. Ni-catalysed coupling of N-alkyl-2,4,6-triphenylpyridinium reagents (Katritzky salts) with aryl halides are then compared under chemical reaction conditions, using Zn or Mn reductants, and under electrochemical conditions performed at applied potentials corresponding to the Zn and Mn reduction potentials and at potentials optimized to achieve the maximum yield. The collective results illuminate the important role of reductant redox potential in Ni-catalysed XEC reactions.

锌和锰广泛用作合成方法中的还原剂，例如镍催化的交叉亲电子偶联（XEC）反应，但它们在有机溶剂中的氧化还原电位未知。在这里，我们展示了如何使用开路电势测量来确定 Zn 和 Mn 在不同有机溶剂中以及在常见反应添加剂存在下的热力学电势。分析了这些 Zn 和 Mn 电势对一对 Ni 催化反应的影响，每个反应都显示出对两种还原剂中的一种的偏好。然后，在化学反应条件下，使用 Zn 或 Mn 还原剂，以及在与 Zn 对应的外加电位下进行的电化学条件下，比较N-烷基-2,4,6-三苯基吡啶鎓试剂（Katritzky 盐）与芳基卤化物的镍催化偶联。和 Mn 还原电位以及优化电位以实现最大产率。集体结果阐明了还原剂氧化还原电位在镍催化 XEC 反应中的重要作用。