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]
Roemmele, Tracey L.
Boeré, René T.
Voltammetric studies of S2N2 employing both cyclic voltammetry (CV) and rotating disc electrode (RDE) methods on GC electrodes at RT revealed two irreversible reduction processes at ca. −1.4 V and −2.2 V in CH3CN, CH2Cl2 and THF (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 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 voltages, spectra from transient adsorbed radicals are observed. In moist solvent or with added HBF4, a longer-lived spectrum is obtained due to the neutral radical [S2N2H]•, identified by simulation of the EPR spectrum and DFT calculations. The chemical reduction of S2N2 with Na[C10H8] or Na[Ph2CO] produces [Na(15-crown5)][S3N3], while reduction with cobaltocene gives [Cp2Co][S3N3]. The X-ray structure of the former reveals a strong interaction (Na···N = 2.388(5) Å) between the crown ether-encapsulated Na+ cation and one of the nitrogen atoms of the essentially planar six-membered cyclic anion [S3N3]−.
Sherpa Romeo white journal. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher.
Electrochemistry , Chemical reduction , Disulfur dinitride , EPR spectroscopy , DFT calculations
Roemmele, T. L., Konu, J., Boeré, R. T., & Chivers, T. (2009). 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]. Inorganic Chemistry, 48(19), 9454–9462. doi:10.1021/ic9014114