Inorganic-organic hybrid compounds provide a class of materials displaying interesting technological impor- tance [1] . The abilities to combine the properties of organic and inorganic compounds within one single mole- cular scale leads to interesting crystal structures [2] . In these materials, the crystal packing is ensured by hy- drogen bonds and π-π stacking interactions. These non-covalent weak forces play a vital role in molecular recog- nition, self organization of molecule and highly efficient and specific biological reactions associated with supra- molecular chemistry [3] . In this area, transition metal complexes are known to be effective against rheumatoid arthritis and they also show anti-ulcer activity [4] [5] . These complexes have different molecular geometries, such as tetrahedral, square planar, square pyramidal, trigonal bipyramidal and octahedral [6] .

As part of our continued involvement in the investigation of metal complexes of nitrogen containing ligands such as, e.g. Schiff bases [7] , we report here the synthesis and characterization of two new Zn(II) complex with the monodentate ligand methyl-(2-pyridin-2-yl-ethyl)-ammonium.

Single crystal X-ray diffraction analysis reveals that the structure of the title compound is characterized by an isolated structure, based on the protonated 2-(2-methylaminoethyl)pyridine, methyl-(2-pyridin-2-yl-ethyl)-am- monium, ligand coordinating to a zinc atom that is further terminally bonded by three chlorine atoms as in Figure 1. The methylenic group adjacent to the aliphatic nitrogen atom forms a weak intramolecular C-H…Cl hydrogen bond with the Cl1 hydrogen atom. This compound is a so called “zwitterions”, where the positive charge is localized at the protonated aliphatic nitrogen atom of the methyl-(2-pyridin-2-yl-ethyl)-ammonium moiety and the negative charge in the vicinity of three chlorine atoms. All the crystallographically independent atoms are in general positions. The Zn atom has a slightly distorted tetrahedronal geometry, coordinationg with the aromtic nitrogen atom of the cationic ligand and three terminal chlorine atoms (Figure 2). The Zn-Cl distances range from 2.2338(10) to 2.2828(8) Å and the Zn-N of 2.0690(18) Å (Table 2), which are comparable to those reported [12] - [15] . The bond angles of Cl-Zn-Cl and N-Zn-Cl range from 104.60 (3) to 117.74 (3), which are close to those in a regular tetrahedron, agree with that previously described [16] . In the atomic arragment, the ZnNCl₃ tetrahedra form corrugated chains extending along the b-axis (Figure 3). These chains are located at (1/2, 0, 1/4) and (1/2, 0, 3/4) (Figure 4). The organic entities are inserted between these chains through N-H…Cl, C-H…Cl and C-H…N hydrogen bonds to form layers parallel to (b, c) plan (Figure 5, Table 3). These layers are situated at x = n/2 (Figure 6). A perspective view of the whole atomic arrangment is given in Figure 7. It should be pointed out that between the hydrogen bonds two are bifurcated N2―H2A・・・(Cl1ⁱ, Cl2 ⁱ) and N2―H2B・・・(Cl2ⁱⁱ, Cl3ⁱⁱ) (for symmetry codes, see Table 3).

Symmetry codes: (i) x, −y+1/2, z + 1/2; (ii) −x + 1, y + 1/2, −z + 1/2; (iii) ?x + 1, y − 1/2, −z + 1/2; (iv) −x, y + 1/2, −z + 1/2.

A novel complex ZnCl₃ (methyl-(2-pyridin-2-yl-ethyl)-ammonium) has been synthesized at room temperature and characterized by single crystal X-ray diffraction. In the crystal structure of the title compound, the Zn(II) ion is tetracoordinated to one nitrogen atom of the monodentate cationic ligand and to three chlorine ligands. All the components of this material are interconnected via N-H∙∙∙Cl, C-H∙∙∙Cl and C-H∙∙∙N hydrogen bonds to form layers parallel to the (b, c) plan.

Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Centre, CCDC No 1035723. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK: fax: (+44) 01223-336-033; e-mail: deposit@ccdc.cam.ac.

We would like to thank the Tunisian Secretariat of State for Scientific Research and Technology for its financial support.