Abstract
In the title compound, C4H6N3 (+)center dot H2O4P-center dot H2O, the pyrimidinium ring is essentially planar, with an r.m.s. deviation of 0.0016 angstrom. In the structure, pairs of symmetry-related anions are connected into centrosymmetric clusters via strong O-H center dot center dot center dot O hydrogen bonds forming six-membered rings with an R (2) (2)(6) motif. These clusters are interconnected via water molecules through OW-H center dot center dot center dot O hydrogen bonds, building an infinite layer parallel to the ab plane. Moreover, infinite chains of 2-aminopyrimidinium cations spread along the a-axis direction. These chains are connected to the inorganic layer through N-H center dot center dot center dot O, C-H center dot center dot center dot O and C-H center dot center dot center dot N hydrogen bonds, which, together with electrostatic and van der Waals interactions, contribute to the cohesion and stability of the network in the crystal structure.