Electrochemistry of Nickel Complexes with Phosphorylated Dithiocarbamate in Aqueous Media

The redox behavior of nickel complexes with sulfur-containing ligands remains of considerable interest due to their significant value in coordination chemistry, catalysis, and bioorganic modeling. In this context, it is important to investigate how aqueous media and acid–base equilibria influence the stability and transformation pathways of such complexes. In this work, the electrochemical behavior of nickel complexes with phosphorylated dithiocarbamate was studied using cyclic voltammetry at various scan rates and pH values. Compared to similar systems in organic solvents, the complexes exhibited additional oxidation and reduction signals, indicating coupled chemical steps. The pH dependence of these peaks confirmed the role of hydroxo groups in the oxidation processes. Varying the scan rate revealed competition between ligand exchange pathways. At low and moderate scan rates, tris-dithiocarbamate nickel(III/IV) complexes are formed, whereas at higher scan rates, hydroxo-containing compounds make a greater contribution. Based on the experimental results and standard redox potentials derived from quantum chemical calculation data, a general scheme for the resulting electrochemical processes was proposed. The results demonstrate the key role of aqueous media and pH in regulating the redox process of nickel complexes with phosphorylated dithiocarbamate.