Bis(2,4,6-triamino-1,3,5-triazin-1-ium) pyrazine-2,3-dicarboxyl-ate tetra-hydrate: a synchrotron radiation study.

The title compound, 2C(3)H(7)N(6) (+)·C(6)H(2)N(2)O(4) (2-)·4H(2)O or (tataH)(2)(pzdc)·4H(2)O, was synthesised by a reaction between pyrazine-2,3-dicarboxylic acid (H(2)pzdc) as a proton donor and 2,4,6-triamino-1,3,5-triazin (tata) as a proton acceptor. In the crystal structure, an extensive series of O-H⋯O, O-H⋯N, N-H⋯O and N-H⋯N hydrogen bonds generates a three-dimensional framework with the hydrogen bonding involving most donor and acceptor centers. π-π stacking inter-actions are also observed between adjacent triazine rings, with centroid-centroid distances of 3.4994†(8) and 3.5922†(7)†à .