4-Methylbenzaldehyde thiosemicarbazone

The title compound, C9H11N3S, was prepared by reacting 4-methylbenzaldehyde with thiosemicarbazide. An intramolecular N—H⋯N hydrogen bond helps to establish the observed molecular conformation. The crystal packing is realized by intermolecular N—H⋯S hydrogen bonds.

Experimental Crystal data

Comment
Thiosemicarbazones constitute an important class of N,S donor ligands due to their ability to react with a wide range of metals (Casas et al., 2000). Thiosemicarbazones exhibit various biological activities and have therefore attracted considerable pharmaceutical interest (Maccioni et al., 2003;Ferrari et al., 2000). They have been evaluated as antiviral, antibacterial and anticancer therapeutics. Thiosemicarbazones belong to a large group of thiourea derivatives, whose biological activities are a function of the parent aldehyde or ketone moiety (Chimenti et al., 2007). Schiff bases in general show potential as antimicrobial and anticancer agents (Tarafder et al., 2000;Deschamps et al., 2003) and have therefore envisaged biochemical and pharmacological applications. We are focusing our synthetic and structural studies on new products of thiazole Schiff bases from thiosemicarbazones (Zhang et al., 2009). We herein report the crystal structure of the title compound (I).
The atom-numbering scheme of (I) is shown in Fig.1, and all bond lengths are within normal ranges (Allen et al., 1987).
The sulfur atom and the hydrazine nitrogen N1 are in trans position with respect to the C9-N2 bond. The molecular conformation is determined by a strong intramolecular hydrogen bond N3-H3A···N1(2.641 (3) A°).

Experimental
A mixture of 4-methyl-benzaldehyde (1.20 g, 0.01 mol) and hydrazinecarbothioamide (0.91 g, 0.01 mol) in 20 ml of absolute methanol was refluxed for about 3 h. After cooling, the precipitated solid separated was filtered and recrystallized from ethyl acetate. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of ethyl acetate at room temperature.

Data collection
Enraf-Nonius CAD-4 diffractometer R int = 0.032 Radiation source: fine-focus sealed tube θ max = 25.3º Monochromator: graphite θ min = 1.7º T = 293 K h = −15→0 ω/2θ scans k = 0→9 Absorption correction: ψ scan (North et al., 1968) l = −11→12 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 Rfactors(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.