Bipyridine complexes of Ni are used as catalysts in a variety of reductive transformations. Here, the electroreduction of [Ni(Mebpy) 3 ] 2+ (Mebpy = 4,4’‐dimethyl‐2,2’‐bipyridine) in dimethylformamide is reported, with the aim of determining the redox mechanism and oxidation states of products formed under well‐controlled electrochemical conditions. Results from cyclic voltammetry, steady‐state voltammetry (SSV) and chronoamperometry demonstrate that [Ni(Mebpy) 3 ] 2+ undergoes two sequential 1 e reductions at closely separated potentials ( E 0’ 1 = ‐1.06 ± 0.01 V and E 0 ’ 2 = ‐1.15 ± 0.01 V vs Ag/AgCl (3.4 M KCl)). Homogeneous comproportionation to generate [Ni(Mebpy) 3 ] + is demonstrated in SSV experiments in low ionic strength solutions. The comproportionation rate constant is determined to be > 10 6 M ‐1 s ‐1 , consistent with rapid outer‐sphere electron transfer. Consequentially, on voltammetric time scales, the 2 e reduction of [Ni(Mebpy) 3 ] 2+ results in formation of [Ni(Mebpy) 3 ] 1+ as the predominant species released into bulk solution. We also demonstrate that [Ni(Mebpy) 3 ] 0 slowly loses a Mebpy ligand (~10 s ‐1 ).

中文翻译：

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[Ni（Mebpy）3] 2+的电化学还原。在低离子强度溶液中通过循环伏安法和稳态伏安法阐明氧化还原机理

Ni的联吡啶配合物在各种还原转化中用作催化剂。在此，报道了在二甲基甲酰胺中[Ni（Mebpy）3] 2+（Mebpy = 4,4'-二甲基-2,2'-联吡啶）的电还原，目的是确定所形成产物的氧化还原机理和氧化态在良好控制的电化学条件下。循环伏安法，稳态伏安法（SSV）和计时安培法的结果表明[Ni（Mebpy）3] 2+在紧密分开的电势下经历了两个连续的1 e降低（E 0'1 = ‐1.06±0.01 V和E 0' 2 = ‐1.15±0.01 V（相对于Ag / AgCl（3.4 M KCl））。在低离子强度溶液中的SSV实验中证明了生成[Ni（Mebpy）3] +的均匀相称。确定比例比例常数> 10 6 M -1 s -1，与快速外层电子转移相一致。因此，在伏安时间尺度上，[Ni（Mebpy）3] 2+的2 e还原导致形成[Ni（Mebpy）3] 1+作为释放到本体溶液中的主要物质。我们还证明了[Ni（Mebpy）3] 0缓慢失去了Mebpy配体（〜10 s -1）。