Structural characterization of two tetra-chlorido-zincate salts of 4-carb-oxy-1-imidazol-3-ium: a salt hydrate and a co-crystal salt hydrate.

Imidazole-containing compounds exhibit a myriad of pharmacological activities. Two tetra-chlorido-zincate salts of 4-carb-oxy-1-imidazol-3-ium, ImHCOH, are reported. Bis(4-carb-oxy-1-imidazol-3-ium) tetra-chlorido-zincate monohydrate, (CHNO)[ZnCl]·HO, (I), crystallizes as a monohydrate salt, while bis-(4-carb-oxy-1-imidazol-3-ium) tetra-chlorido-zincate bis-(1-imidazol-3-ium-4-carboxyl-ato) monohydrate, (CHNO)[ZnCl]·2CHNO·HO, (II), is a co-crystal salt with six residues: two ImHCOH cations, two formula units of the zwitterionic 1-imidazol-3-ium-4-carboxyl-ate, ImHCO, one tetra-chlorido-zincate anion and one water mol-ecule disordered over two sites in a 0.60 (4):0.40 (4) ratio. The geometric parameters of the ImHCOH and the ImHCO moieties are the same within the standard uncertainties of the measurements. Both compounds exhibit extensive hydrogen bonding, including involvement of the tetra-chlorido-zincate anion, resulting in inter-connected chains of anions joined by water mol-ecules.