Hexakis(melaminium) tetrakis(dihydrogenphosphate) monohydrogenphosphate tetrahydrate

The crystal structure of the new melaminium salt, hexa­kis(2,4,6‐tri­amino‐1,3,5‐triazin‐1‐ium) tetrakis­(di­hydrogenphos­phate) mono­hydrogenphosphate tetrahydrate, 6C₃H₇N₆⁺·4H₂PO₄^?·HPO₄^2?·4H₂O, is built up from singly protonated melaminium residues, di­hydrogenphosphate and mono­hydrogen­phosphate anions, and water mol­ecules. The melaminium residues are interconnected by four N—H?N hydrogen bonds, forming chains along the 001] direction. These chains of melaminium residues form stacks aligned along 100]. The di­hydrogenphosphate anions interact with the mono­hydrogenphosphate anions via the H atoms and, together with hydrogen‐bonded dimers of the water mol­ecules, develop layers parallel to the (010) plane. The oppositely charged moieties interact via multiple N—H?O hydrogen bonds that stabilize the stacking structure.