2-Cycloheptylidene-N-phenylhydrazinecarbothioamide

In the title compound, C14H19N3S, the seven-membered cycloheptane ring adopts a chair conformation. An intramolecular N—H⋯N hydrogen bond [graph-set motif S(5)] is present in the N—N—C—N chain between the ring systems. An intramolecular C—H⋯S contact also occurs. In the crystal, pairs of molecules form centrosymmetric dimers through N—H⋯S hydrogen bonds [graph-set R 2 2(8)]. These dimers are connected by C—H⋯S interactions with an R 2 2(14) motif.

In the title compound, C 14 H 19 N 3 S, the seven-membered cycloheptane ring adopts a chair conformation. An intramolecular N-HÁ Á ÁN hydrogen bond [graph-set motif S(5)] is present in the N-N-C-N chain between the ring systems. An intramolecular C-HÁ Á ÁS contact also occurs. In the crystal, pairs of molecules form centrosymmetric dimers through N-HÁ Á ÁS hydrogen bonds [graph-set R 2 2 (8)]. These dimers are connected by C-HÁ Á ÁS interactions with an R 2 2 (14) motif.

Comment
Thiosemicarbazones constitute an important class of N, S-donor ligands, and their coordination chemistry was initially explored in the early sixties (Gingras et al., 1961;Ali & Livingstone, 1974;Lobana et al., 2009). On other hand, depending on the parent aldehyde or ketone, the corresponding thiosemicarbazone scaffolds have been evaluated over the last 50 years as anti-viral, anti-bacterial and anti-cancer therapeutic agents (Hu et al., 2006;Du et al., 2002;Lovejoy & Richardson, 2002). Based on these facts and following our study of cyclization reactions of thiosemicarbazides we report the synthesis and crystal structure of the title compound.
In the crystal, pairs of molecules form centrosymmetric dimers through intermolecular N-H···S hydrogen bonds [graph-set R 2 2 (8)]. These dimers are also connected by C-H···S interactions with an R 2 2 (14) motif.

Experimental
A solution of 1 mmol (112 mg) of cycloheptanone in 5 ml DMSO was added dropwise to a solution of 1 mmol (167 mg) of N-phenylhydrazinecarbothioamide in 5 ml of DMSO. The reaction mixture was stirred for 2 h at ambient temperature and then left to stand overnight. The resulting mixture was poured into 250 ml of ice/water to give a white precipitate.
The crude product was filtered off, washed with cold ethanol and recystallized from ethanol to furnish colourless crystals suitable for X-ray diffraction. M.p. 379 K.

Refinement
All H atoms were found in a difference map. All C-bonded H-atoms were positioned geometrically and refined using a riding model [C-H = 0.95 (aromatic H) and 0.99 Å (methylene H)], with U iso (H) = 1.2 U iso (C). The N-bonded H-atoms were refined freely.

Computing details
Data collection: APEX2 (Bruker, 2013); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009   The molecular structure of the title compound with 50% probability displacement ellipsoids. Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.