3-(p-Tolyl)-4-{3-[(phenylamino)methyl]-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl}sydnone

In the title compound, C20H17N7O2S (systematic name: 3-(4-methylphenyl)-4-{3-[(phenylamino)methyl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazin-6-yl}-1,2,3-oxadiazol-3-ium-5-olate), the 3,6-dihydro-2H-1,3,4-thiadiazine ring adopts a half-boat conformation. The oxadiazol-3-ium ring makes dihedral angles of 57.99 (6) and 54.48 (6)° with the phenyl and benzene rings, respectively, while the 1,2,4-triazole ring forms corresponding angles of 37.35 (6) and 73.89 (6)°. The dihedral angle between the oxadiazol-3-ium and 1,2,4-triazole rings is 21.12 (6)°. In the crystal, the molecules are linked via intermolecular N—H⋯O and C—H⋯N hydrogen bonds into a layer parallel to the (100) plane. The crystal structure is further consolidated by C—H⋯π interactions. An intramolecular C—H⋯O hydrogen bond is also observed, which generates an S(6) ring motif.

The bond lengths (Allen et al., 1987) and angles in the molecule ( Fig. 1) are within normal ranges. The molecular structure is stabilized by an intramolecular C10-H10A···O2 hydrogen bond which generates an S(6) ring motif (Bernstein et al., 1995).
Crystals suitable for X-ray analysis were obtained from 1:2 mixtures of DMF and ethanol by slow evaporation.

Refinement
H1 was located in a difference Fourier map and refined using a riding model with U iso (H) = 1.2 U eq (N). The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.97 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating-group model was applied for the methyl group. The highest residual electron density peak is located at 0.68 Å from C18 and the deepest hole is located at 1.01 Å from N4. Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme. The intramoleculer hydrogen bond is shown as dashed line.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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 > 2sigma(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.