ChemInform Abstract: Electrochemical and Chemical Reduction of Disulfur Dinitride: Formation of [S4N4]-·, EPR Spectroscopic Characterization of the [S2N2H]·Radical, and X-Ray Structure of [Na(15-crown-5)][S3N3]

Voltammetric studies of S2N2 employing both cyclic voltammetry (CV) and rotating disk electrode (RDE) methods on GC electrodes at room temperature (RT) revealed two irreversible reduction processes at about −1.4 V and −2.2 V in CH3CN, CH2Cl2, and tetrahydrofuran (vs ferrocene) and no observable oxidation processes up to the solvent limit when the scan is initially anodic. However, after cycling the potential through −1.4 V, two new couples appear near −0.3 V and −1.0 V due to [S3N3]−/0 and [S4N4]−/0 respectively. The diffusion coefficient D for S2N2 was determined to be 9.13 × 10−6 cm2 s−1 in CH2Cl2 and 7.65 × 10−6 cm2 s−1 in CH3CN. Digital modeling of CVs fits well to a mechanism in which [S2N2]−• couples rapidly with S2N2 to form [S4N4]−•, which then decomposes to [S3N3]−. In situ electron paramagnetic resonance (EPR) spectroelectrochemical studies of S2N2 in both CH2Cl2 and CH3CN resulted in the detection of strong EPR signals from [S4N4]−• when electrolysis is conducted at −1.4 V; at more negative vol...