N,N,N′,N′-Tetramethylethylenediammonium tetrachloridozincate

The asymmetric unit of the title compound, (C6H18N2)[ZnCl4], consists of one tetrachloridozincate anion and two half-N,N,N′N′-tetramethylethylenediammonium cations. Each of the two diammonium cations is located about an inversion center and one of them is disordered over two sets of sites in a 0.780 (17):0.220 (17) ratio. The ZnII atom has a slightly distorted tetrahedral coordination environment. The cations and anions are connected via N—H⋯Cl hydrogen bonds into chains extending along [0-11].

The asymmetric unit of the title compound, (C 6 H 18 N 2 ) [ZnCl 4 ], consists of one tetrachloridozincate anion and two half-N,N,N 0 N 0 -tetramethylethylenediammonium cations. Each of the two diammonium cations is located about an inversion center and one of them is disordered over two sets of sites in a 0.780 (17):0.220 (17) ratio. The Zn II atom has a slightly distorted tetrahedral coordination environment. The cations and anions are connected via N-HÁ Á ÁCl hydrogen bonds into chains extending along [011].

Comment
The organic-inorganic hybrid salts consisting of organic cation and polyhalometal counter anions have received considerable attention because of their potential applications in analytical, material and supramolecular chemistry (Al-Ktaifani et al., 2011). In this work, we report the crystal structure of one such compound. The title compound was obtained unexpectedly during an attempt to synthesize a mixed-ligand zinc(II) complex of N,N,N′N′-tetramethylethylenediamine and 2-mercaptosuccinic acid. The crystal structure of the title hybrid material is shown in Fig. 1. The structure is ionic and the asymmetric unit consists of one tetrachloridozincate anion and two halves of tetramethylethylenediammonium cations, located on inversion centers. The Zn atom, coordinated by four chloride anions, shows a distorted tetrahedral environment (Fig. 1). The bond angles around zinc vary from 105.93 (7)° to 115.80 (7)°. The compound is isostructural with its cobalt analogue (Baughman et al., 2011). In the crystal,the cations and anions are linked by N-H···Cl hydrogen bonds into chains propagating along the [011] direction (Fig. 2).

Experimental
The title complex was prepared by adding 0.12 g (1.0 mmol) of N,N,N′N′-tetramethylethylenediamine in 10 ml methanol to an aqueous solution (5 ml) of 0.14 g (1.0 mmol) zinc chloride. The slightly turbid solution was stirred for 15 minutes.
Then a solution of 0.16 g (1.0 mmol) 2-mercaptosuccinic acid in 15 ml was added. The mixture was stirred for 30 minutes along with heating. The white mixture obtained was filtered and the filtrate was kept at room temperature for crystallization. As a result, white crystalline product was obtained, that was washed with methanol.

Refinement
The H1N atom of one of the symmetry independent cations was located on a difference Fourier map and freely refined.
All other H atoms were placed in calculated positions with a C-H distance of 0.96 Å (U iso (H) = 1.5U eq (C)) for methyl groups, 0.97 Å (U iso (H) = 1.2U eq (C)) for methylene groups and N-H distance of 0.91 Å (U iso (H) = 1.2U eq (H)) for the other NH group. One of the diammonium cations the atoms C1, C2 and C3 are disordered over two positions, with the occupancy of the major position of 0.780 (17). During the refinement process restraints were imposed on C-N bond distances in the disordered cation.

N,N,N′,N′-Tetramethylethylenediammonium tetrachloridozincate
Crystal data (C 6  Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 R-factors(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.