(Z)-N,N-Dimethyl-2-[phenyl(pyridin-2-yl)methylidene]hydrazinecarbothioamide

The title compound, C15H16N4S, exists in the Z conformation with the thionyl S atom lying cis to the azomethine N atom. The shortening of the N—N distance [1.3697 (17) Å] is due to extensive delocalization with the pyridine ring. The hydrazine–carbothioamide unit is almost planar, with a maximum deviation of 0.013 (2) Å for the amide N atom. The stability of this conformation is favoured by the formation of an intramolecular N—H⋯N hydrogen bond. The packing of the molecules involves no classical intermolecular hydrogen-bonding interactions; however, a C—H⋯π interaction occurs.

The title compound, C 15 H 16 N 4 S, exists in the Z conformation with the thionyl S atom lying cis to the azomethine N atom. The shortening of the N-N distance [1.3697 (17) Å ] is due to extensive delocalization with the pyridine ring. The hydrazine-carbothioamide unit is almost planar, with a maximum deviation of 0.013 (2) Å for the amide N atom. The stability of this conformation is favoured by the formation of an intramolecular N-HÁ Á ÁN hydrogen bond. The packing of the molecules involves no classical intermolecular hydrogenbonding interactions; however, a C-HÁ Á Á interaction occurs.
KJ thanks the UGC, New Delhi, for the award of a Teacher Fellowship. The authors also thank the STIC, CUSAT, Kochi-22, for providing the single-crystal XRD data.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2463).  (Beraldo & Gambino, 2004). Derivatives of hydrazinecarbothioamide constitute an important group of multidentate ligands with potential binding sites available for a wide variety of metal ions. These thiourea derivatives find substantial applications in different facets of contemporary scientific research.
The title compound (Z)-2-N,N-dimethyl-2-[phenyl(pyridin-2-yl)methylidene]hydrazinecarbothioamide is found to exist in Z configuration. A perspective view of the molecular structure of the title compound, along with the atom-labeling scheme, is given in Fig. 1. The S1= C13-N3-N2 torsion-angle [14.4 (2)°] indicates that thionyl atom S1 is positioned cis to azomethane nitrogen atom N2. The hydrazinecarbothioamide moiety adopts an extended conjugation, with electron delocalization throughout the N4/C13/S1/N3/N2 group. The fact that the compound exists in the thione form is confirmed by the N3-N2, N4-C13 and C13=S1 bond distances. The C13=S1 bond distance is close to that expected for a C=S double bond of 1.60 Å (Huheey et al., 1993). The N3-N2 bond distance is very close to the reported similar substituted hydrazinecarbothioamide (Joseph et al., 2004). The resonance form involving pyridine ring would account for the shortening of the N-N distance through extensive electron delocalization.
The hydrazinecarbothioamide moiety, comprising atoms N3, C13, S1 and N4, is almost planar with the maximum deviation of 0.013 (2) Å for atom N4. The pyridyl ring and phenyl ring are not in the same plane and the pyridyl ring is twisted significantly from the hydrazinecarbothioamide plane, with a torsionl angle of -176.3 (2)°.
Two types of intramolecular (classical and non-classical) hydrogen bond interactions are found in this molecule. A classical hydrogen bonding interaction between the hydrogen attached to the N3 nitrogen and the N1 nitrogen with the D···A distance of 2.602 (2) Å and the non-classical hydrogen bonding interaction between one of the hydrogen atom attached to the C14 atom and the S1 atom of the molecule with a D···A distance of 3.030 (2) Å as described in Table 1. Fig. 2 shows the packing diagram of the title compound. Packing of these molecules does not include any classical intermolecular hydrogen bonding interactions in its molecular array. However, it may be directed by the C-H···π interaction between the pyridine ring and the hydrogen attached at C5 carbon atom of the phenyl ring of the another molecule. There are four very weak π-π interactions present in this molecular array with the distances of 5.5874 (17), 4.8708 (15), 5.5455 (17) and 4.9165 (15) Å between the centroids of the corresponding rings involving interactions.

Experimental
The title compound was prepared by adapting a reported procedure (Joseph et al., 2006) by refluxing a mixture of methanolic solutions of 2-benzoylpyridine (11 mmol, 2.032 g) and N,N-dimethylhydrazinecarbothioamide (11 mmol, 1.320 g) for five hours after adding 5 drops of acetic acid. Yellow crystals were collected, washed with few drops of methanol and dried supplementary materials sup-2 over P 4 O 10 in vacuo. Single crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation from its methanolic solution.

Refinement
All H atoms on C were placed in calculated positions, guided by difference maps, with C-H bond distances 0.93-0.96 Å.
H atoms were assigned as U iso =1.2Ueq (1.5 for Me). N3-H3' hydrogen was located from difference maps and restrained using DFIX instruction. Fig. 1. The molecular structure of the title compound with displacement ellipsoids are drawn at 50% probability level.  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.