(E)-4-(2,3-Dihydro-1,3-benzothiazol-2-ylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one

In the title compound, C17H13N3OS, the dihedral angle between the ring systems is 2.22 (5)°. The N—H grouping participates in both intra- and intermolecular N—H⋯O hydrogen bonds, the latter leading to dimers related by a twofold rotation axis.

In the title compound, C 17 H 13 N 3 OS, the dihedral angle between the ring systems is 2.22 (5) . The N-H grouping participates in both intra-and intermolecular N-HÁ Á ÁO hydrogen bonds, the latter leading to dimers related by a twofold rotation axis.

Comment
The chemistry of pyrazole derivatives has been the subject of much interest due to their importance for various applications and their widespread potential and proven biological and pharmacological activities such as anti-inflammatory (Tewari et al., 2001), antimicrobial, antiviral (Harnden et al., 1978), anti-tumor (Hatheway et al., 1978), anti-fungal and pesticidal substances (Londershausen et al., 1996).
In the pyrazol moiety the shortening of the bond between N12 and C13 [1.307 (2) Å] corresponds to a double bond in accordance with the formulation of the double bond in scheme 1.
All of the three subunits are for themselves planar, deviations from the least-square planes are small. Within the benzo[d]thiazole the greatest deviations result from the fact that the phenyl ring is planar whereas the remaining atoms of the thiazole ring are out of this plane with a maximum at C2 [-0.055 (2) Å]. Moreover, the complete molecule adopts are slightly curved conformation (Fig. 2). In the case of the 1,3-benzothiazole-pyrazole bond planarity should be result from the double bond [d(C-C) = 1.388 (2) Å] between the two subunits. Nevertheless, the interplanar dihedral angle between both ring systems is 2.22 (5)°. Between the pyrazole and the phenyl fragment the carbon-carbon single bond is shortened [d(C-C) = 1.416 (2) Å] but even longer than a double bond. In this case, the interplanar dihedral angle between both fragments is 7.16 (6)°. Similar values between these two subunits were obsereved earlier (Liu et al. 2004).
In the solid state, 3 forms dimers ( Fig. 3) by bifurcated hydrogen bonds between the NH-group [N3] of the 1,3-benzothiazole-rest and O15 of a neighbouring molecule, both related by a twofold rotation axis. The second part of the bifurcated hydrogen bond system combines the NH-group with O15 within the same molecule.
supplementary materials sup-2 Refinement Hydrogen atoms were clearly identified in difference Fourier syntheses, idealized and refined at calculated positions riding on the carbon atoms with C-H = 0.98 Å for methyl H atoms, 0.95 Å for aromatic H atoms and N-H = 0.88 Å. Methyl groups were allowed to rotate around the C-C-bond. Three common isotropic displacement parameters for the H-atoms of the three different subunits were refined. Fig. 1. Ball-and-stick model of 3 with the atomic numbering scheme used; with exception of the hydrogen atoms, which are shown as spheres with common isotropic radius, all other atoms are represented as thermal displacement ellipsoids showing the 50% probability level of the corresponding atom.   (E)-4-(2,3-Dihydro-1,3-benzothiazol-2-ylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one

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