Bis(tetraethylammonium) hydrogensulfate dihydrogenphosphate at 292 and 150 K

The title compound, 2C₈H₂₀N⁺·HSO₄⁻·H₂PO₄⁻, was crystallized in a desiccator over P₄O₁₀ 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 O⃛O 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—H⃛O 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 O⃛O 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.