4-Chloroanilinium hydrogen (2R,3R)-tartrate monohydrate

In the structure of the hydrated 1:1 compound of 4-chloroaniline with L-tartaric acid, C6H7ClN+center dot C4H5O6-center dot H2O, determined at 130 K, the asymmetric unit comprises two 4-chloroanilinium cations, two hydrogen tartrate anions and two water molecules of solvation, and forms a two-dimensional duplex substructure comprising head-to-tail C-1(1)(7) hydrogen-bonded hydrogen tartrate anions and water molecules. The pi-associated 4-chloroanilinium cation pairs [ring centroid separation = 3.576 (4) angstrom; inter-ring dihedral angle = 0.5 (1)degrees] are accommodated within the channels of the substructure and are hydrogen-bonded to it peripherally.