1-(2,5-Dimethylphenyl)piperazine-1,4-diium tetrachloridozincate monohydrate

In the title compound, (C12H20N2)[ZnCl4]·H2O, the two piperazine N atoms are protonated and the [ZnCl4]2− anions adopt a slightly distorted tetrahedral configuration. In the crystal, O—H⋯Cl hydrogen bonds link the tetrachloridozincate anions and the water molecules into corrugated inorganic chains parallel to [010]. The crystal structure is stabilized by N—H⋯Cl, N—H⋯O and O—H⋯Cl hydrogen bonds, with the N—H hydrogen bond originating from one of the two N atoms being trifurcated.

In the title compound, (C 12 H 20 N 2 )[ZnCl 4 ]ÁH 2 O, the two piperazine N atoms are protonated and the [ZnCl 4 ] 2À anions adopt a slightly distorted tetrahedral configuration. In the crystal, O-HÁ Á ÁCl hydrogen bonds link the tetrachloridozincate anions and the water molecules into corrugated inorganic chains parallel to [010]. The crystal structure is stabilized by N-HÁ Á ÁCl, N-HÁ Á ÁO and O-HÁ Á ÁCl hydrogen bonds, with the N-H hydrogen bond originating from one of the two N atoms being trifurcated.

Related literature
For common applications of organic-inorganic hybrid materials, see: Dai et al. (2002); Tao et al. (2003). For a related structure and discussion of geometrical features, see: Ben Gharbia et al. (2007). For the geometry around the zinc atom, see: Harrison (2005).
No π-π stacking interactions between the phenylene rings or C-H···π interactions towards them are observed. In the organic entity, the piperazine-1,4-diium ring adopts a typical chair conformation and all the geometrical features agree with those found in 1-(2,3-dimethylphenyl)piperazinium tetrachlorozincate(II) monohydrate (Ben Gharbia et al., 2007). It is worth noticing that in the [ZnCl 4 ] 2anion, the Zn-Cl bond lengths and Cl-Zn-Cl bond angles are not equal to one another, but vary with the environment around the Cl atom with Zn-Cl bond lengths between 2.2619 (4) and 2.2857 (4) Å. In the title compound, all the chloride ions are involved in hydrogen bonding. However, only the Cl4 chloride atom participates in two N-H···Cl bonds, and the Zn1-Cl4 bond distance is with 2.2857 (4) Å the longest (Table 1). The Cl-Zn-Cl angles range between 105.803 (16) and 112.737 (17)°. These values indicate that the coordination geometry of the Zn atom can be regarded as being a slightly distorted tetrahedron (Harrison, 2005).

Experimental
A mixture of an aqueous solution of 1-(2,5-dimethyphenyl)piperazine (2 mmol, 0.380 g), zinc chloride (2 mmol, 0.396 g) and HCl (10 ml, 0.4 M) in a Petri dish was slowly evaporated at room temperature. Single crystals of the title compound, suitable for X-ray diffraction analysis, were obtained after several days by slow evaporation at room temperature (yield 68%).

Refinement
Reflection (0 0 1) was obscured by the beamstop and was omitted from the refinement. C-H hydrogen atoms were placed in calculated positions with C-H distances in the range 0.93-0.97 Å. The water hydrogen atom positions were refined with O-H distance restraints of 0.84 (2) Å, and the N-H distance of N1 to 0.91 (2) Å. The U iso (H) values of all H atoms were constrained to 1.2 or 1.5 times U eq of the respective parent atom. Fig. 1. A view of the title compound, showing 50% probability displacement ellipsoids, arbitrary spheres for the H atoms, and the atom numbering scheme.  1-(2,5-Dimethylphenyl)piperazine-1,4-diium tetrachloridozincate monohydrate