(1E,2E)-2-Methyl-3-phenylacrylaldehyde thiosemicarbazone

In the crystal structure of the title compound, C11H13N3S, molecules form centrosymmetric synthons with an R 2 2(8) graph-set motif, linked by pairs of N—H⋯S hydrogen bonds. The synthons are connected through further N—H⋯S hydrogen bonds, extending the packing to form a two-dimensional network lying parallel to (001). In addition, C—H⋯π interactions are observed.

In the crystal structure of the title compound, C 11 H 13 N 3 S, molecules form centrosymmetric synthons with an R 2 2 (8) graph-set motif, linked by pairs of N-HÁ Á ÁS hydrogen bonds. The synthons are connected through further N-HÁ Á ÁS hydrogen bonds, extending the packing to form a twodimensional network lying parallel to (001). In addition, C-HÁ Á Á interactions are observed.
Cg1 is the centroid of the C1-C6 ring.
In general the molecular crystals of thiosemicarbazones are formed by hydrogen bonds interaction through -NH-C(S)-NH-N= fragment, forming in many cases synthons. (Lima et al., 2002). Even though that C=S···H-N hydrogen bond is weaker than its C=O···H-N analogue, the effective electronegativity of S is increased by conjugative interactions between C=S and the lone pair of one or more N substituents this effect is called resonance-induced hydrogen bonding at sulfur acceptor (Allen et al. 1997). This properties have been widely exploited in supramolecular chemistry, where it has been used as a building block for anion receptors (Kearney et al., 1998).
Centrosymmetric synthons (R 2 2 (8)) (Bernstein et al., 1995) are connected through N-H···S hydrogen bond to extend packing along the a axis (Fig 2). Intermolecular C-H···π interactions are also present in the crystal and contribute to stabilize the packing along c axis. (Fig.3).

Experimental
A solution of trans-alfa-methylzimaldehyde (1.4619 g, 0.01 mol) and thiosemicarbazide (0.9144 g 0.01 mol) in absolute methanol (50 ml) was refluxed for 3 h in the presence of p-toluenesulfonic acid as catalyst, with continuous stirring. On cooling to room temperature the precipitate was filtered off, washed with copious cold methanol and dried in air. White single crystals of compound (I) were obtained after recrystallization from a solution in methanol.

Refinement
All H atoms located at the difference Fourier maps and isotropically refined. At the end of the refinement the highest peak in the electron density was 0.199 eÅ -3 , while the deepest hole was -0.153 eÅ -3 .

Computing details
Data collection: CrysAlis CCD (Oxford Diffraction, 2010); cell refinement: CrysAlis CCD (Oxford Diffraction, 2010); data reduction: CrysAlis RED (Oxford Diffraction, 2010); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 1999), PLATON (Spek, 2009), PARST95 (Nardelli, 1995) and publCIF (Westrip, 2010).      where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.20 e Å −3 Δρ min = −0.15 e Å −3 Special details Experimental. Absorption correction: CrysAlis RED (Oxford Diffraction, 2010), Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(F 2 ) is used only for calculating R-factors(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.