Nuclear magnetic resonance- and electron paramagnetic resonance spectroscopic characterization of S4N4 and (SN)x dissolved in [EMIm][OAc]

Abstract

This work focuses on the reaction mechanism of poly(sulfur nitride) ((SN)x, (S15N)x), with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [EMIm][OAc]. We compare this with the reaction of the IL with S4N4 or its 15N-labeled form S415N4, a precursor for the synthesis of (SN)x and (S15N)x. After purification of the S4N4–IL- and S415N4–IL systems via column chromatography, we characterized the reaction products with 1H, 13C, and 15N nuclear magnetic resonance spectroscopy and with electron spray ionization time-of-flight mass spectrometry. Furthermore, time-resolved electron paramagnetic resonance spectroscopy and time-resolved ultraviolet–visible spectroscopy were carried out. Thus, radical intermediates were detected, which were consumed with reaction time. Finally, we postulate a reaction mechanism for the S4N4–IL- and S415N4–IL systems and compare this with the respective data for the (SN)x −IL- and (S15N)x–IL-systems.