Crystal structure of 2-[(E)-2-(2-chlorobenzylidene)hydrazin-1-yl]-4-phenyl-1,3-thiazole

The asymmetric unit of the title compound, C16H12ClN3S, contains two independent molecules whose conformations differ primarily in the orientations of the phenyl and chlorobenzene rings with respect to the thiazole ring. In the first molecule, the dihedral angles are 3.0 (1) and 9.2 (1)°, respectively, for the phenyl ring and the chlorobenzene ring, while in the second molecule, the corresponding angles are 18.6 (1) and 23.4 (1)°. In the crystal, the two independent molecules are associated via complementary N—H⋯N hydrogen bonds into a dimer. These dimers are associated through weak C—H⋯Cl and C—H⋯S interactions into supramolecular chains propagating along the a-axis direction.


S1. Comment
Thiazole containing compounds have been reported to possess large number of biological properties (Siddiqui et al., 2011;Siddiqui et al., 2009). Sulfathiazol (antimicrobial drug), Ritonavir (antiretroviral drug), Abafungin (antifungal drug), Bleomycine and Tiazofurin (antineoplastic drug) are common drugs with thiazole-based structures. Alagebrium (formerly known as ALT-711) is also a thiazolium salt which was the first drug used for breaking the protein crosslinks caused by advanced glycation endproducts (AGEs). Through this effect Alagebrium is designed to reverse the stiffening of blood vessel walls that contributes to hypertension and cardiovascular disease (Bakris et al., 2004;Little et al., 2005).
İn this context and as part of our study in synthesis of potential bioactive heterocyclic molecules, we report the synthesis and crystal structure of the title compound.
There are two independent molecules of the title compound in the asymmetric unit whose conformations differ primarily in the orientations of the phenyl rings with respect to the thiazole ring. For molecule 1, the dihedral angles are 3.0 (1) and 9.2 (1)°, respectively, for rings C1-C6 and C11-C16 while for molecule 2 the corresponding angles are 18.6 (1) and 23.4 (1)°.
In the crystal structure, the two independent molecules are associated via complementary N-H···N hydrogen bonds ( Fig. 1 and Table 1). These pairs are associated into chains running along the a axis through weak C-H···Cl interactions (Table 1) and weak C-H···S interactions (Table 1).

S2. Experimental
The title compound has been prepared according to our reported method (Mohamed et al., 2013). Colourless crystals suitable for X-ray diffraction have been obtained by crystallization of the crude product (I) from ethanol.

S3. Refinement
H-atoms attached to carbon were placed in calculated positions (C-H = 0.95 Å) while those attached to nitrogen were placed in locations derived from a difference map and, following initial independent refinement to verify their presence, their coordinates were adjusted to give N-H = 0.91 Å. All were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms.

Figure 1
The asymmetric unit with the complementary N-H···N hydrogen bonds shown as dotted lines. Ellipsoids are drawn at the 50% probability level.