N‐methyl‐4,4’‐bipyridinium (Mebipy+) can be reduced in two separate one electron steps in 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI). The first reduction product Mebipy, a radical species, is shown to have no significant interaction with dissolved CO2. In contrast, the second reduction product, Mebipy‐, forms an adduct with CO2. This adduct has a relatively strong C‐N bond from nucleophilic interaction of the non‐quaternized nitrogen of the anion with the electrophilic carbon of CO2. These interactions are characterized using density functional theory (DFT). During electrochemical reduction of Mebipy+ in the presence of dissolved CO2, this strong interaction of Mebipy‐ drives a disproportionation reaction in which two Mebipy radicals react to produce Mebipy+ and Mebipy‐, which subsequently reacts with CO2 to form the nitrogen‐bound adduct, Mebipy‐CO2‐, a type of carbamate. This electrochemical DISP mechanism is simulated, providing a good fit with experimental results. The overall stoichiometry for the electrochemical capture and release of CO2 in this system is that two electrons are required to bind one equivalent of CO2.

中文翻译：

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N-甲基-4,4'-联吡啶鎓还原形式与CO2相互作用的实验，模拟和计算研究

N-甲基-4,4'-联吡啶（Mebipy +）可以在1-丁基-1-甲基吡咯烷鎓双（三氟甲基磺酰基）酰亚胺（BMPTFSI）中分两个单独的电子步进行还原。第一种还原产物Mebipy是一种自由基物质，与溶解的CO2没有明显的相互作用。相反，第二种还原产品Mebipy‐与CO2形成加合物。该加合物由于阴离子的非季铵化氮与CO2的亲电子碳之间的亲核相互作用而具有相对较强的C-N键。这些相互作用使用密度泛函理论（DFT）进行表征。在溶解的CO2存在下电化学还原Mebipy +的过程中，Mebipy-的这种强相互作用引起歧化反应，其中两个Mebipy自由基反应生成Mebipy +和Mebipy-，随后会与CO2反应形成氮结合的加合物Mebipy-CO2-（一种氨基甲酸酯）。模拟了这种电化学DISP机理，与实验结果非常吻合。在该系统中，电化学捕获和释放CO2的总体化学计量是需要两个电子才能结合一当量的CO2。