Benzimidazolines Convert Sulfur Dioxide to Bisulfate at Room Temperature and Atmospheric Pressure Utilizing Aerial Oxygen

By
employing a simple strategy of reacting SO2 gas with
easily attainable hydride donors such as 2-substituted-1,3-dimethyl-2,3-dihydro-1H-benzo­[d]­imidazole, benzimidazoline and
SO2 were converted into benzimidazolium bisulfate at room
temperature and atmospheric pressure. Bisulfate originated from SO2 and hydride from benzimidazoline and aerial oxygen. Metastable
dimers of bisulfate anions were observed in the solid state and in
solution where the anions are not stabilized by encapsulation in cages
but through hydrogen bonding from benzimidazolium cations. All three
benzimidazolines and resulted benzimidazolium bisulfates have been
characterized using 1H and 13C NMR spectroscopy,
high-resolution electrospray ionization mass spectrometry, and single
crystal X-ray diffraction techniques.