Crystal structure of 4-methyl-N-[(4-methylpyridin-2-yl)carbamothioyl]benzamide

In the title compound, C15H15N3OS, intramolecular N—H⋯O and C—H⋯S hydrogen bonds both generate S(6) rings. The C=O and C=S bonds lie to opposite sides of the molecule. In the crystal, inversion dimers linked by pairs of N—H⋯S hydrogen bonds generate (8) loops.

In the title compound, C 15 H 15 N 3 OS, the dihedral angle between the planes of the benzene and pyridine rings is 26.86 (9) . Intramolecular N-HÁ Á ÁO and C-HÁ Á ÁS hydrogen bonds both generate S(6) rings. The C O and C S bonds lie to opposite sides of the molecule. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁS hydrogen bonds generate R 2 2 (8) loops.

Chemical context
The role of benzoyl thiourea derivatives in coordination chemistry has been extensively studied and quite satisfactorily elucidated. As benzoyl thioureas have suitable C O and C S functional groups, they can be considered as useful chelating agents due to their ability to encapsulate metal ions into their coordinating moiety. Thiourea and its derivatives have found extensive applications in the fields of medicine, agriculture and analytical chemistry. Thioureas are also known to exhibit a wide range of biological activities including anticancer (Saeed et al., 2010a), antifungal (Saeed et al., 2010b) and as agrochemicals (Xu et al., 2003). As part of our studies in this area, we now describe the synthesis and structure of the title compound, (I).

Structural commentary
The title compound (Fig. 1) is a benzoyl thiourea derivative and analogous to a compound recently reported by us (Adam et al., 2014), except that the other substituent is changed to methylpyridine and the thiourea moiety is still in a para position. The dihedral angle between the planes of the benzene and pyridine rings is 26.86 (9) . The C O bond length of 1.225 (2) Å is comparable to that observed in N-benzoyl-N 0 -phenylthiourea (Hassan et al., 2008a). The C-N bond lengths are in the range 1.328 (2)-1.417 (2) Å , shorter than the normal single C-N bond length (1.469 Å ), indicating partial double-bond character owing to the resonance effect at the carbonylthiourea moiety.

Supramolecular features
In the crystal of (I), inversion dimers linked by pairs of N-HÁ Á ÁS hydrogen bonds (Table 1, Fig. 2) generate R 2 2 (8) loops. As free rotation about the N1-C7 and N2-C8 single bonds is hindered, the C O and C S bonds are unlikely to align at the same side of the molecule in order to form a chelate with a metal ion.

Synthesis and crystallization
The title compound was prepared according to a slight modification of the method described by Hassan et al. (2008b). p-Benzoyl chloride (13 mmol) was added dropwise to a stirred acetone solution (30 ml) of ammonium thiocyanate (13 mmol). The mixture was stirred for 10 min. A solution of 2-amino-4-picoline in acetone was added and the reaction mixture was refluxed for 3 h, after which the solution was poured into a beaker containing some ice cubes. The resulting precipitate was collected by filtration, washed several times with a cold ethanol/water mixture and purified by recrystallization from an ethanol solution.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The H-atoms on the N atoms were located in a difference-Fourier map and were freely refined. All other H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.96 Å and U iso (H) = 1.2U eq (aromatic C) or 1.5U eq (methyl C).

Figure 2
The crystal packing of the title compound viewed down the c axis. Hydrogen bonds are shown as dashed lines.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 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.