4-Benzyl-3-(thiophen-2-yl)-4,5-dihydro-1H-1,2,4-triazole-5-thione

In the title compound, C13H11N3S2, the triazole and thiophene rings are coplanar [dihedral angle = 6.22 (13)°]. By contrast, the phenyl ring is perpendicular to the triazole ring [dihedral angle = 85.58 (13)°], so that the molecule has an L-shape. The thiophene S atom is syn with the ring imine N atom. In the crystal, eight-membered {⋯HNCS}2 synthons form between centrosymmetrically related molecules, leading to dimeric aggregates that are connected into a supramolecular layer parallel to (101) by π–π interactions between centrosymmetrically related triazole rings [centroid–centroid distance = 3.6091 (15) Å] and C—H⋯π interactions.

Cg1 is the centroid of the C8-C13 ring.
In (I), Fig. 1, the triazole ring is plane (r.m.s. deviation = 0.008 Å) and the thione-S2 atom lies 0.030 (1) Å out of the plane. The thiophene ring is co-planar with the triazole ring [dihedral angle = 6.22 (13)°] and the latter forms a dihedral of 85.58 (13)° with the phenyl ring. The thiophene-S1 atom is syn with the ring imine-N2 atom. Overall, the molecule has the shape of the letter L. A similar conformation was found in the analogous furanyl compound for which two molecules comprise the asymmetric unit and which was characterized as an hydrate (Zareef et al., 2008).
In the crystal packing, centrosymmetrically related molecules aggregate into dimers via N-H···S hydrogen bonds that lead to eight-membered {···HNCS} 2 synthons, Table 1. The dimers are connected into rows along the b axis by π-π interactions between centrosymmetrically related triazole rings [inter-centroid distance = 3.6091 (15) Å for symmetry operation: 1 -x, 1 -y, 1 -z]. Projecting out on either side of the row are the phenyl groups that inter-digitate with translationally related rows to enable the formation of edge-to-face C-H···π interactions, Table 1, that result in a supramolecular layer parallel to (1 0 1), Fig. 2. Layers stack with no specific interactions between them, Fig. 3.

Experimental
A mixture of thiophene-2-carbohydrazide (1.42 g, 0.01 mol), benzyl isothiocyanate (1.49 g, 0.01 mol), in ethanol (10 ml) was heated under reflux with stirring for 1 h after which the solvent was distilled off in vacuo. Aqueous sodium hydroxide solution (10%, 15 ml) was added to the residue and the mixture was heated under reflux for 2 h then filtered hot. On cooling, the mixture was acidified with hydrochloric acid and the precipitated crude product was filtered, washed with water, dried and crystallized from aqueous ethanol to yield 2.32 g (85%) of the title compound as colourless crystals. M.pt: 515-517 K. Single crystals suitable for X-ray analysis were obtained by slow evaporation of its

Figure 1
The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 35% probability level.  A view of the supramolecular layer in (I), which is sustained by N-H···S hydrogen bonds as well as by π-π and C-H···π interactions shown as orange, blue and purple dashed lines, respectively.

Figure 3
View of the unit-cell contents in projection down the b axis of (I), highlighting the stacking of layers. The N-H···S hydrogen bonds as well as by π-π and C-H···π interactions shown as orange, blue and purple dashed lines, respectively.

4-Benzyl-3-(thiophen-2-yl)-4,5-dihydro-1H-1,2,4-triazole-5-thione
Crystal data C 13 H 11 N 3 S 2 M r = 273.37 Monoclinic, P2 1 /n Hall symbol: -P 2yn a = 13.422 (2) Å b = 6.1670 (7)  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 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.