Structural and supramolecular interactions of 2-aminothiazolium 3,5-dinitrobenzoate monohydrate.

Abstract

The hydrated salt 2-aminothiazolium 3,5-dinitrobenzoate monohydrate, C₃H₅N₃S⁺·C₇H₃N₂O₆^-·H₂O, was synthesized and its structure characterized with single-crystal X-ray diffraction and Hirshfeld surface analysis. In the crystal structure, proton transfer from the carboxylic acid group of the 3,5-dinitrobenzoic acid (DNBA) molecule to the thiazole N atom of the 2-aminothiazole (AT) molecule results in salt formation. The protonation is supported by a widened C-N(H)-C ring bond angle. The primary supramolecular synthon is a heterodimeric R₂²(8) ring motif formed via N-H...O hydrogen bonds. The lattice water molecules play a key role in assembling tetrameric [R₄²(9)] and hexameric [R₆⁵(17)] motifs through N-H...O, OW-HW...O, OW-HW...OW and C-H...OW interactions. These units propagate into hydrogen-bonded chains along the b axis via water-water interactions, which are further linked through C-H...O contacts to generate a 3D network incorporating a large R₈⁸(40) ring motif. The crystal structure is further stabilized by carbonyl-π interactions. Hirshfeld surface analysis reveals prominent red spots in the d_norm mapping, indicating strong O-H...O and N-H...O contacts. 2D fingerprint plots confirm the dominance of O...H/H...O interactions, supporting their important role in the cohesion and stability of the crystal structure.