Bis(tetraethylammonium) hydrogensulfate dihydrogenphosphate at 292 and 150 K

The title compound, 2C(8)H(20)N(+) x HSO(4)(-) x H(2)PO(4)(-), was crystallized in a desiccator over P(4)O(10) from a water solution of stoichiometric amounts of tetraethylammonium hydroxide and sulfuric and phosphoric acids. The compound is deliquescent. The structure contains two symmetry-independent cations in nearly the same conformation, as well as two symmetry-independent anions, the central atoms of which are equally occupied by P and S. The anions are interconnected by short O...O hydrogen bonds into one-dimensional chains. The distances and angles between some of the methyl or methylene groups and anionic O atoms indicate the presence of C-H...O hydrogen bonds. The structure was determined from data at 292 (2) and 150 (2) K. These room- and low-temperature structures are virtually the same, with the exception of the localization of the H atoms that participate in the symmetry-restricted O...O hydrogen bonds. A differential scanning calorimetry experiment indicated no phase transition below the temperature at which the compound started to decompose (353 K), down to 93 K.