Structural characterization of two tetra­chlorido­zincate salts of 4-carb­oxy-1H-imidazol-3-ium: a salt hydrate and a co-crystal salt hydrate

Imidazole-containing compounds exhibit a myriad of pharmacological activities. Two tetra­chlorido­zincate salts of 4-carb­oxy-1H-imidazol-3-ium, ImHCO(2)H(+), are reported. Bis(4-carb­oxy-1H-imidazol-3-ium) tetra­chlorido­zincate monohydrate, (C(4)H(5)N(2)O(2))(2)[ZnCl(4)]·H(2)O, (I), crystallizes as a monohydrate salt, while bis­(4-carb­oxy-1H-imidazol-3-ium) tetra­chlorido­zincate bis­(1H-imidazol-3-ium-4-carboxyl­ato) monohydrate, (C(4)H(5)N(2)O(2))(2)[ZnCl(4)]·2C(4)H(4)N(2)O(2)·H(2)O, (II), is a co-crystal salt with six residues: two ImHCO(2)H(+) cations, two formula units of the zwitterionic 1H-imidazol-3-ium-4-carboxyl­ate, ImHCO(2), one tetra­chlorido­zincate anion and one water mol­ecule disordered over two sites in a 0.60 (4):0.40 (4) ratio. The geometric parameters of the ImHCO(2)H(+) and the ImHCO(2) moieties are the same within the standard uncertainties of the measurements. Both compounds exhibit extensive hydrogen bonding, including involvement of the tetra­chlorido­zincate anion, resulting in inter­connected chains of anions joined by water mol­ecules.