(S)-1,2,4-Trimethylpiperazine-1,4-diium tetrachloridozincate(II)

In the title compound, (C7H18N2)[ZnCl4], the Zn atom adopts a slightly distorted tetrahedral geometry. The diprotonated piperazine ring adopts a chair conformation. In the crystal structure, the cations and anions are linked by intermolecular N—H⋯Cl hydrogen bonds into a chain along [001].

In the title compound, (C 7 H 18 N 2 ) [ZnCl 4 ], the Zn atom adopts a slightly distorted tetrahedral geometry. The diprotonated piperazine ring adopts a chair conformation. In the crystal structure, the cations and anions are linked by intermolecular N-HÁ Á ÁCl hydrogen bonds into a chain along [001].

Comment
The existence of a chiral centre in an organic ligand is very important for the construction noncentrosymmetric or chiral coordination polymers that exhibit desirable physical properties such as ferroelectricity (Fu et al., 2007) and nonlinear optical second harmonic generation (Qu et al., 2003). Chiral (S)-2-methylpiperazine has a chiral centre which have shown tremendous scope in the synthesis of transition-metal complexes (Ye et al., 2009). The construction of new members of this family of ligands is an important direction in the development of modern coordination chemistry. We report here the crystal structure of the title compound The asymmetric unit of the title compound, (C 7 H 18 N 2 )[ZnCl 4 ] ( Fig.1), consists of one 1,2,4-trimethylpiperazinium cation and one ZnCl 4 2anion. The Zn atom adopts a slightly distorted tetrahedral geometry. The diprotonated piperazine ring adopts a chair conformation with Cremer & Pople (1975) puckering parameters : Q T =0.5673 (3)Å, θ = 1.8 (3)° , φ= 67 (10)°. In the crystal structure, cations and anions are linked by intermolecular N-H···Cl hydrogen bonds into a one-dimensional chain viewed along the c-axis with set graph-motif C 2 2 (9) (Bernstein, et al., 1995) (Fig.2).

Experimental
A mixture of (S)-1,2,4-trimethylpiperazine quinine (1 mmol, 0.128 g), ZnCl 2 (1 mmol, 0.136 g) and 10% aqueous HCl (6 ml) were mixed and dissolved in 20 ml water by heating to 363 K (15 min) forming a clear solution. The reaction mixture was cooled slowly to room temperature, crystals of the title compound were formed after 8 days.

Refinement
All H atoms were placed in calculated positions, with C-H = 0.93-0.98Å and N-H = 0.90 Å, and refined using a riding model, with U iso (H)=1.2U eq (C,N) or 1.5 U eq (C) for methyl H atoms.
Figures Fig. 1. The asymmetric unit of the title compound with atom labels. Displacement ellipsoids were drawn at the 30% probability level supplementary materials sup-2 Crystal data (C 7