Synthesis and crystal structure of the pyridinium acid nitrate [(PyH)2(NO3)][H2(NO3)3] containing a dihydrogen trinitrate anion

A new protic room-temperature ionic liquid (Tc=14 ± 1°C) – pyridinium hydrogen dinitrate – was obtained from a solution of pyridinium nitrate in anhydrous nitric acid in a desiccator with P2O5. According to single crystal X-ray diffraction data, the solid state structure of [(PyH)2(NO3)][H2(NO3)3] consists of hydrogen bonded cations [(PyH)2(NO3)]+ and anions [(NO3)(HNO3)2]− with a previously unknown configuration containing two HNO3 molecules linked via hydrogen bonds to the central NO3− anion by the sin–anti type.