A serendipitous product of the reaction of famotidine with copper(II).

Reaction of CuCl2 and the anti-ulcer drug famotidine in aqueous solution results in hydrolytic cleavage of the organic mol-ecules with loss of sulfonamide fragments and subsequent crystallization of a new Cu complex, di-chlorido-{3-[(2-guanidino-thia-zol-4-yl)methyl-sulfan-yl]propanoic acid}copper(II) monohydrate, [CuCl2(C8H12N4O2S2)]·H2O (1). The CuII ions adopt a square-pyramidal environment with the basal plane comprising one chloride ion and the organic ligand acting as the N,N,S-donor bis-chelate tridentate group. The second chloride ion resides in the apical position and it completes the electrically neutral complex. The supra-molecular landscape is dominated by conventional hydrogen bonding involving strong hydrogen-bond donors and acceptors [O(N)H⋯O and O(N)H⋯Cl], which assemble the complex units and solvent water mol-ecules into bilayers parallel to the bc plane. The primary significance of the contacts with H atoms was assessed with the results of Hirshfeld analysis, which suggest a 51.3% contribution of such contacts to the surface of individual complex mol-ecules. The relatively short chalcogenide bonds [S⋯O = 3.006 (2) Å] and NH2 (guanidine)-π inter-actions are also relevant to the packing. The chemical identity of 1 and the bulk sample is confirmed by elemental analysis, IR spectroscopic and thermogravimetric data.