Crystal structure of propane-1,3-diaminium squarate dihydrate

The crystal structure of propane-1,3-diaminium squarate dihydrate (space group P4bm, Z = 2) features a triperiodic N—H⋯O and O—H⋯O hydrogen-bond network with a polar c axis.

Propane-1,3-diaminium squarate dihydrate, C₃H₁₂N₂²⁺·C₄O₄²⁻·2H₂O, results from the proton-transfer reaction of propane-1,3-di­amine with squaric acid and subsequent crystallization from aqueous medium. The title compound crystallizes in the tetra­gonal crystal system (space group P4bm) with Z = 2. The squarate dianion belongs to the point group D_{4 h} and contains a crystallographic fourfold axis. The propane-1,3-diaminium dication exhibits a C_{2 v}-symmetric all-anti conformation and resides on a special position with mm2 site symmetry. The orientation of the propane-1,3-diaminium ions makes the crystal structure polar in the c-axis direction. The solid-state supra­molecular structure features a triperiodic network of strong hydrogen bonds of the N—H⋯O and O—H⋯O types.