Elektrochemische untersuchung von bis(diphenyldithiophosphin) disulfid

The electrochemical behaviour of bis(diphenyldithiophosphine)disulphide (RSSR) and mercuric diphenyldithiophosphinate [(RS)₂Hg] in ethanol-lithium perchlorate and ethanol-sulphuric acid media was studied by the methods of classical polarography, and electrolysis at controlled-potential and at a rotating disc platinum electrode. The data obtained show that RSSR is not reduced directly on the dropping mercury electrode but is adsorbed. It then undergoes a rapid chemical reaction causing the formation of (RS)₂Hg, which is electroactive. The electrolysis at controlled potential proves that (RS)₂Hg undergoes a two-electron reduction, giving diphenyldithiophosphinic acid (RSH) as a main product, whereas the oxidation of RSH leads to the production of (RS)₂Hg. Regardless of the fact that the chemical and adsorption equilibria during reduction of RSSR and (RS)₂Hg are complex, the coulometric generation of RSH is not difficult to achieve, and permits the use of RSSR as a coulometric reagent.