Bis(2,4,6-tri­amino­pyrimidin-1-ium) sulfate penta­hydrate

The asymmetric unit of the title salt, 2C(4)H(8)N(5) (+)·SO(4) (2−)·5H(2)O, contains four 2,4,6-tri­amino­pyrimidinium (TAPH(+)) cations, two sulfate anions and ten lattice water mol­ecules. Each two of the four TAPH(+) cations form dimers via N—H⋯N hydrogen bonds between the amino groups and the unprotonated pyrimidine N atoms [graph-set motif R (2) (2)(8)]. The (TAPH(+))(2) dimers, in turn, form slightly offset infinite π–π stacks parallel to [010], with centroid–centroid distances between pyrimidine rings of 3.5128 (15) and 3.6288 (16) Å. Other amino H atoms, as well as the pyrimidinium N—H groups, are hydrogen-bonded to sulfate and lattice water O atoms. The SO(4) (2−) anions and water mol­ecules are inter­connected with each other via O—H⋯O hydrogen bonds. The combination of hydrogen-bonding inter­actions and π–π stacking leads to the formation of a three-dimensional network with alternating columns of TAPH(+) cations and channels filled with sulfate anions and water mol­ecules. One of the sulfate anions shows a minor disorder by a ca 37° rotation around one of the S—O bonds [occupancy ratio of the two sets of sites 0.927 (3):0.073 (3)]. One water mol­ecule is disordered over two mutually exclusive positions with an occupancy ratio of 0.64 (7):0.36 (7).