The electrochemical reduction of S -phenyl benzenethiosulfonate ( 1 ) was investigated by cyclic voltammetry at different scan rates (0.1–60 V/s) using glassy carbon electrodes in three different solvents; acetonitrile, dimethyl sulfoxide, and dimethyl formamide. The initial electron transfer (ET) to the investigated compound follows a concerted process with the formation of a radical/ion pair before complete dissociation (“sticky” dissociative ET mechanism). Application of classical and “sticky” dissociative electron transfer theories, as well as theoretical calculations supported the proposed ET mechanism. The theoretical calculations showed that the LUMO of S -phenyl benzenethiosulfonate and SOMO of its reduced form are homed on the S-SO₂ chemical bond with a low contribution on the rest of the molecule. This indicates that the incoming electron is directly injected to the chemical bond causing its cleavage. The controlled potential electrolysis of the investigated compound, monitored by high performance liquid chromatography and cyclic voltammetry, indicated the consumption of one electron per molecule, and final formation of diphenyl disulfide and phenyl sulfinate. All experimental and theoretical findings were used to propose the full reduction mechanism. Also, a solvent effect was observed on certain parameters including reduction peak potentials, transfer coefficient values, the strength of the interaction between the ion/radical fragments, and the chemical reaction processes following the first ET. This solvent effect was rationalized by comparison of the solvent’s properties.

中文翻译：

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溶剂对 S- 苯基苯硫代磺酸盐电化学还原的影响

使用循环碳伏安法在三种不同溶剂中使用玻璃碳电极，通过循环伏安法研究了 S- 苯基苯硫代磺酸盐（ 1 ）的电化学还原 。乙腈，二甲基亚砜和二甲基甲酰胺。到被研究化合物的初始电子转移（ET）遵循一致的过程，在完全离解之前形成自由基/离子对（“粘性”离解ET机制）。经典和“粘性”离解电子转移理论的应用以及理论计算支持了所提出的ET机制。理论计算表明， S- 苯基苯硫代磺酸盐的LUMO 及其还原形式的SOMO位于S-SO上₂化学键，对分子其余部分的贡献很小。这表明进入的电子被直接注入到化学键中导致其裂解。通过高效液相色谱和循环伏安法监测的受控化合物的电势电解表明，每个分子消耗一个电子，并且最终形成了二苯基二硫化物和苯基亚磺酸盐。所有的实验和理论发现均被用来提出完整的还原机理。同样，在某些参数上观察到了溶剂效应，包括还原峰电位，转移系数值，离子/自由基片段之间相互作用的强度以及第一次ET之后的化学反应过程。