NMR Spectral Studies of Interactions Between the Accelerants SPS and MPS and Copper Chlorides

Proton and C-13 NMR spectroscopic studies of possible interactions of the copper electroplating accelerant disodium bis(3-sulfopropyl)disulfide (SPS) and its reduced form sodium 3-mercaptopropylsulfonate (MPS) with both cuprous chloride and cupric chloride were carried out in with reagent concentrations between millimolar and under anaerobic conditions. It was confirmed that MPS reacted with CuCl to yield Cu(I)–thiolate products. No evidence for formation of a solution Cu(I)–SPS complex from CuCl and SPS was found. Instead, a redox reaction yielded a Cu(I)–thiolate along with Cu(II) with an estimated equilibrium constant of . The previously reported reaction of aqueous cupric chloride with MPS was investigated further under anaerobic conditions. In addition to SPS, Cu(I)–thiolate products similar to those from the CuCl/MPS reaction were identified. The reaction was found to be complete only upon addition of over 2 equiv of MPS. No evidence for any interaction between and SPS was observed.