(NH₄)₇(HPO₄)₂(PO₄), hepta­ammonium bis­(hydrogenphosphate) phosphate

The asymmetric unit of the compound (NH₄)₇(HPO₄)₂(PO₄) consists of two hydrogen phosphate anions, one phosphate anion and seven ammonium cations, all of them located in general positions. The two [PO₃(OH)]²⁻ anions are linked to the PO₄³⁻ anion via an O—H...O hydrogen bond to form a three-anion unit, which is surrounded by the ammonium cations. The anions and cations are further connected via N—H...O hydrogen bonding.