5-(4-Fluorophenyl)-3-(4-methylphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide

The central pyrazole ring in the title compound, C17H16FN3S, adopts an envelope conformation with the methine C atom bearing the 4-fluorophenyl substituent as the flap atom. Whereas the tolyl ring is slightly twisted out of the least-squares plane through the pyrazole ring [dihedral angle = 13.51 (11)°], the fluorobenzene ring is almost perpendicular [dihedral angle = 80.21 (11)°]. The thioamide group is almost coplanar with the N—N bond of the ring [N—N—C—N torsion angle = 1.2 (3)°] and the amine group forms an intramolecular hydrogen bond with a ring N atom. In the crystal, supramolecular double layers in the bc plane are formed via N—H⋯S, N—H⋯F and C—H⋯F interactions.

The central pyrazole ring in the title compound, C 17 H 16 FN 3 S, adopts an envelope conformation with the methine C atom bearing the 4-fluorophenyl substituent as the flap atom. Whereas the tolyl ring is slightly twisted out of the leastsquares plane through the pyrazole ring [dihedral angle = 13.51 (11) ], the fluorobenzene ring is almost perpendicular [dihedral angle = 80.21 (11) ]. The thioamide group is almost coplanar with the N-N bond of the ring [N-N-C-N torsion angle = 1.2 (3) ] and the amine group forms an intramolecular hydrogen bond with a ring N atom. In the crystal, supramolecular double layers in the bc plane are formed via N-HÁ Á ÁS, N-HÁ Á ÁF and C-HÁ Á ÁF interactions.
We thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR-MOHE/SC/12).
The central pyrazolyl ring in (I), Fig. 1, adopts an envelope conformation with the methine-C7 atom being the flap atom. The tolyl ring is slightly twisted out of the least-squares plane through the pyrazolyl ring, forming a dihedral angle of 13.51 (11)°. By contrast, the fluorobenzene ring is almost perpendicular to the five-membered ring [dihedral angle = 80.21 (11)°]. Finally, the thioamide residue is co-planar with the N2-N1-C17-N3 torsion angle being 1.2 (3)°; the amine group is orientated towards the ring-N2 atom, forming a hydrogen bond, Table 1. Similar conformations have been observed in related structures bearing two six-membered rings (Nonthason et al., 2011;Chantrapromma et al., 2012).
The F atom proves to be pivotal in providing stability to the crystal structure of (I). Thus, in addition to forming an intramolecular N-H···N2 hydrogen bond, the amine-H31 atom forms a hydrogen bond to the F1 atom, Table 1. The second amine-H32 atom hydrogen bonds to a thione so that a supramolecular chain along the c axis ensues, Fig. 2.
Chains stack along the b axis to form a row and centrosymmetrically related rows inter-digitate along the a axis allowing for the formation methylene-C16-H···F1 interactions and, therefore, double layers, Fig. 2.
The resultant solid was filtered and dried. Re-crystallization was by slow evaporation of DMF solution of (I) which yielded colourless crystals in 61% yield. M.pt: 513-514 K.

Refinement
Nitrogen-and carbon-bound H-atoms were placed in calculated positions (N-H = 0.88 Å, and C-H 0.93 to 0.98 Å) and were included in the refinement in the riding model approximation, with U iso (H) = 1.2-1.5U equiv (N,C).

Computing details
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).  The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 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 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.