organic compounds
The crystal structure of the title compound, C5H8N3+·C7H4NO4− or (pydaH)+(pydcH)− (pyda is 2,6-diaminopyridine and pydcH2 is pyridine-2,6-dicarboxylic acid), shows both intra- and intermolecular proton transfers from carboxyl groups to the ring N atoms of (pydc)2− and pyda. This determination corrects a previous report which formulated this compound as (pydaH2)2+(pydc)2− [Moghimi, Ranjbar, Aghabozorg, Jalali, Shamsipur, Yap & Rahbarnoohi (2002), J. Mol. Struct. 605, 133–149]. Ion-pairing, hydrogen-bonding and π–π stacking interactions link the fragments to form a self-associated system.