3-(4-Methylphenyl)-4-[(thiosemicarbazono)methyl]-1,2,3-oxadiazol-3-ium-5-olate 1,4-dioxane hemisolvate

The asymmetric unit of the title compound, C11H11N5O2S·0.5C4H8O2, contains one 3-(p-tolyl)sydnone 4-thiosemicarbazone molecule and a half molecule of 1,4-dioxane, which lies abount an inversion centre. The sydnone ring is almost planar, with a maximum deviation of 0.002 (1) Å, and forms a dihedral angle of 46.31 (5)° with the benzene ring. In the crystal, the two components are linked into a tape along [01-1] by N—H⋯O and N—H⋯S hydrogen bonds. The crystal structure is further stabilized by C—H⋯O and C—H⋯π interactions, forming a three-dimensional network.

The asymmetric unit of the title compound, C 11 H 11 N 5 O 2 SÁ-0.5C 4 H 8 O 2 , contains one 3-(p-tolyl)sydnone 4-thiosemicarbazone molecule and a half molecule of 1,4-dioxane, which lies abount an inversion centre. The sydnone ring is almost planar, with a maximum deviation of 0.002 (1) Å , and forms a dihedral angle of 46.31 (5) with the benzene ring. In the crystal, the two components are linked into a tape along [011] by N-HÁ Á ÁO and N-HÁ Á ÁS hydrogen bonds. The crystal structure is further stabilized by C-HÁ Á ÁO and C-HÁ Á Á interactions, forming a three-dimensional network.

sup-1
Acta Cryst. Sydnones are mesoionic heterocyclic aromatic compounds. The study of sydnones still remains a field of interest because of their electronic structures and also because of the varied types of biological activities displayed by some of them (Rai et al., 2008). Recently sydnone derivatives were found to exhibit promising antimicrobial (Jyothi et al., 2008), antiinflammatory (Nithinchandra et al., 2012) and CNS depressant properties (Kalluraya et al., 2001). Since their discovery, sydnones have shown diverse biological activities and it is thought that the meso-ionic nature of the sydnone ring promotes significant interactions with biological systems.

Experimental
To a mixture of 4-formyl-3-(p-tolyl)sydnone (0.01 mol) and thiosemicarbazide (0.01 mol) in ethanol, a catalytic amount of concentrated H 2 SO 4 was added. The solution was stirred at room temperature for 23 h. The solid product that separated out was filtered and dried. The recrystallization of the sample was done using an ethanol-dioxane (1:1 v/v) mixture. The slow evaporation of the ethanol-dioxane mixture of the compound resulted in crystals suitable for X-ray analysis. The remaining H atoms were located geometrically and were refined using a riding model with U iso (H) = 1.2 or 1.5U eq (C) (C-H = 0.95 to 0.99 Å). A rotating group model was applied to the methyl group. In the final refinement, two outliners (-3 6 14 and 1 8 14) were omitted.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids.   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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 1.09153 (