1,1′-(Butane-1,4-diyl)diimidazole-3,3′-diium tetrachloridozincate(II) dihydrate

In the title compound, (C10H16N4)[ZnCl4]·2H2O, the cation lies abouton a center of inversion and the anion about a twofold rotation axis. The ZnII atom is four-coordinate in a tetrahedral environment. The cations, anions and water molecules are linked by N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds into a two-dimensional network.

The Zn II atom lies on an inversion center and is coordinated by four chlorine anions in an tetrahedronal environment( Figure 1). The 1,1'-(1,4-butanediyl)diimidazole molecule also lies on an inversion center and its N atom is protonated.
In the crystal structure, the cations and anions are linked by N-H···Cl hydrogen bonds. In addition, the water molecules are both as acceptor and donor of hydrogen bond link these molecule into a two-dimensional supramolecular network via N-H···O, O-H···Cl hydrogen bonds (Table 1; Figure 2).

Refinement
H atoms bound to C atoms were placed in calculated positions and treated as riding on their parent atoms, with C-H = 0.93 Å (Caromatic) and with U iso (H) = 1.2U eq (C). The N-bound H atoms were located in a difference Fourier map and free refined, Water H atoms were initially located in a difference Fourier map but they were treated as riding on their parent atoms with O-H = 0.85 Å, H···H = 1.39 and with U iso (H) = 1.5U eq (O). Fig. 1. The molecular structure of (I), showing displacement ellipsoids at the 30% probability level for non-H atoms. Dashed lines indicate the intramolecular hydrogen bonding interactions. 1,1'-(Butane-1,4-diyl)diimidazole-3,3'-diium tetrachloridozincate(II) dihydrate

Figures
Crystal data (C 10  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq