organic compounds
The organic acid–base complex 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfonate, C5H14N3+·C7H7O3S−, was obtained from the corresponding 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfinate complex, C5H14N3+·C7H7O2S−, by solid-state oxidation in air. Comparison of the two crystal structures reveals similar packing arrangements in the monoclinic space group P21/c, with centrosymmetric 2:2 tetramers being connected by four strong N—HO=S hydrogen bonds between the imine N atoms of two 1,1,3,3-tetramethylguanidinium bases and the O atoms of two acid molecules.