Tris(2,4,6-triamino-1,3,5-triazin-1-ium) Dihydrogenphosphate Monohydrogenphosphate Tetrahydrate

When recrystallizing the commercial flame retardant melaminium orthophosphate, surprisingly a hydrate with a diverging stoichiometry of melaminium (M) and phosphate (P) was obtained (M(3)P(2)4H(2)O). The structure of M(3)P(2)4H(2)O was solved by single-crystal X-ray diffraction analysis. The arrangement of positive melaminium and negative phosphate layers found in the crystal structure allows for both electrostatic attraction and hydrogen bonding networks. The melaminium layers are comprised of hydrogen-bonded ribbons of melaminium, which in turn are connected by - interactions into layers. The negatively charged phosphate layers are comprised of hydrogen bonded dihydrogenphosphate dimers and hydrogenphosphate dimers, which in turn are interconnected by direct and water-mediated hydrogen bonding into layers.