An orthorhombic polymorph of melaminium chloride hemihydrate

Crystals of an ortho-rhom-bic polymorph of 2,4,6-triamino-1,3,5-triazin-1- ium chloride hemihydrate, C3H7N6 ⁺·Cl^-·0. 5H2O, were obtained by cocrystallization experiments under aqueous acidic conditions (HCl, pH = 2). In the crystal structure, the melaminium ions, chloride anions and water mol-ecules are linked via hydrogen bonds. All H atoms of the melaminium cation are involved in hydrogen bonds. The chloride anions and the water mol-ecules lie on mirror planes. In the c direction, the melaminium ions are stacked by π-π inter-actions.