Melaminium (2-carboxyethyl)(phenyl)phosphinate monohydrate

Abstract

Cocrystallization of melamine (1,3,5-triazine-2,4,6-triamine, ma) with (2-carboxyethyl)(phenyl)phosphinic acid (H2L) from water affords the title compound, C3H7N6+·C9H10O4P−·H2O or (maH)(HL)·H2O, (I). The phosphinic acid H atom of each H2Lmolecule is transferred to a melamine molecule. Structural analysis reveals that there are two types of secondary building units in the crystal structure, namely cationic [(maH+)2]∞ribbons and anionic {[(HL)2(H2O)2]2−}∞layers, the combination of which through hydrogen-bond and electrostatic interactions, generates a large-scale two-dimensional layered structure. The thick layer is sandwich-like, with the central [(maH+)2]∞ribbons being further stabilized by π–π stacking interactions. It is also worthy of note that two conformational isomericR65(24) hydrogen-bond ring motifs can be identified in the {[(HL)2(H2O)2]2−}∞layer.