Bis[methyl 2-(2-pyridylmethylidene)hydrazinecarbodithioato]zinc(II)

In the title compound, [Zn(C8H8N3S2)2], the Zn atom is coordinated by the two ligands in a tridentate manner, via the pyridyl N, the azomethine N and the thiolate S atom; the coordination geometry is distorted octahedral, with the two ligands in the mer configuration (two S atoms and two pyridyl N atoms are cis with respect to each other and the azomethine N atoms is trans). The molecules are linked by C—H⋯S hydrogen bonds, forming a three-dimensional network structure.

In the title compound, [Zn(C 8 H 8 N 3 S 2 ) 2 ], the Zn atom is coordinated by the two ligands in a tridentate manner, via the pyridyl N, the azomethine N and the thiolate S atom; the coordination geometry is distorted octahedral, with the two ligands in the mer configuration (two S atoms and two pyridyl N atoms are cis with respect to each other and the azomethine N atoms is trans). The molecules are linked by C-HÁ Á ÁS hydrogen bonds, forming a three-dimensional network structure.

Experimental
Crystal data [Zn(C 8

Comment
The wide variety of biological activity exhibited by thiosemicarbazones (Kasuga et al., 2001) and Schiff bases derived from S-alkyldithiocarbazates (Akbar Ali et al., 2001) and their interesting coordination chemistry have stimulated considerable research interest in these compounds (Casas et al., 2000). Some Schiff bases of S-alkyl esters of dithiocarbazic acid and their complexes were found to display antifungal and antibacterial properties (Tarafder et al., 2003). Recently we reported the Co(II) complex of the S-containing Schiff base ligand methyl 2-pyridylmethylidenehydrazinecarbodithioate (NNS − ) (Lin et al., 2007). As a part of structural studies of compounds containing the sulfur-nitrogen chelating ligand (Chen et al., 2003a,b), we report here the synthesis and structure of the compound, bis(methyl 2pyridylmethylidenehydrazinecarbodithioato)zinc(II), Zn(NNS) 2 .
The Zn atom is six-coordinated by the two tridentate NNS − anions in a distorted octahedral geometry (Fig. 1). The ligands chelate the Zn(II) ion via the pyridyl N, the azomethine N, and the thiolate S atoms in a mer-configuration with four five-membered rings. The two azomethine N atoms (N2 and N5) are trans to each other, while the sulfur atoms (S1 and S3) and pyridyl N atoms (N1 and N4) are in cis positions. The two almost planar ligands [maximum deviation from their least-squares planes is 0.038 (3) Å] approach the central Zn(II) atom in an orthogonal orientation. The pyridyl ring and the two five-membered chelate rings formed by each ligand display very small dihedral angles between the planes.
The molecules are linked by C-H···S hydrogen bonds. As shown in Fig. 2, each molecular unit forms four acceptor/donor hydrogen bonds with four neighboring molecular units. resulting in a three-dimensional network structure.

Experimental
A solution of Zn(ClO 4 ) 2 (363 mg, 1.00 mmol) in CH 3 OH (20 ml) was slowly added to a solution of methyl 2-pyridylmethylidenehydrazinecarbodithioate (HNNS) (410 mg, 1.95 mmol) in CH 3 OH (10 ml). The resultant black-purple solution was stirred under N 2 for 2 h at 323 K and then filtered. After addition of diethyl ether (20 ml), the filtrate was cooled to 253 K. A microcrystalline solid was collected after 24 h and dried under vacuum (yield: 264 mg, 55%). Brown block-shaped crystals suitable for X-ray diffraction were obtained in 2 d by slow diffusion of diethyl ether into a dilute solution of the title complex in methanol. The assigned structure was substantiated by elemental analysis; calculated for C 16 H 16 N 6 ZnS 4 : C 39.51, H 3.30, N 17.29%; found: C 39.46, H 3.38, N 17.23%.

Refinement
All H atoms were placed in idealized positions (C-H = 0.93 or 0.97 Å), and refined in the riding-model approximation.
U iso (H) = xU eq (carrier atom), where x = 1.5 for methyl and 1.2 for all other H atoms. Fig. 1. The molecular structure of the title compound. Dispacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms have been omitted for clarity. Fig. 2. A view of the three-dimensional molecular network parallel to (010), formed by weak intermolecular C-H···S hydrogen bonds (dotted lines). Hydrogen atoms not involved in hydrogen bonds have been omitted.