4-{3-[(2-Isopropyl-5-methylphenoxy)methyl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazin-6-yl}-3-(p-tolyl)sydnone

In the title triazolothiadiazin compound, C24H24N6O3S (systematic name: 4-{3-[(2-isopropyl-5-methylphenoxy)methyl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazin-6-yl}-3-(4-methylphenyl)-1,2,3-oxadiazol-3-ium-5-olate), an intramolecular C—H⋯O hydrogen bond generates an S(6) ring motif. The two terminal methyl groups of the isopropyl unit are disordered over two sets of positions in a 0.715 (4):0.285 (4) ratio. The mean planes formed through the major and minor disordered isopropyl units are inclined at interplanar angles of 73.1 (4) and 86.6 (8)°, respectively, with the attached phenyl ring. The 3,6-dihydro-1,3,4-thiadiazine ring adopts a twist-boat conformation. The interplanar angle formed between 1,2,3-oxadiazole and 1,2,4-triazole rings is 18.80 (11)°. In the crystal, neighbouring molecules are linked into sheets lying parallel to the bc plane by C—H⋯N hydrogen bonds. Weak intermolecular π–π interactions [centroid–centroid distances = 3.2935 (11) and 3.5590 (12) Å] further stabilize the crystal structure.


Experimental
A solution of triazole (0.01 mol) and 4-bromoacetyl-3-tolylsydnone (0.01 mol) in absolute ethanol (20 ml) was heated under reflux for 10-12 h. The solution was concentrated, cooled to room temperature and neutrallized with 10 % sodium bicarbonate solution. The solid separated was filtered, washed with water, dried and recrystallized from ethanol. Yellow plates of (I) were obtained from a 1:2 mixture of DMF and ethanol by slow evaporation.
supplementary materials sup-2 Refinement Atoms C22 and C23 are disordered over two sites with a refined occupancy ratio of 0.715 (4):0.285 (4). The same U ij parameters were applied for atom pairs C6/C11, C22/C22X and C23/C23X. All hydrogen atoms were placed in their calculated positions, with C-H = 0.93-0.97 Å, and refined using a riding model, with U iso = 1.2 or 1.5 U eq (C). The rotating group model was used for the methyl groups.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems 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.