Preparation and crystal structure of 3-(2-hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine

3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4] thiadiazine, C16H11N5O3S, was prepared by the cyclization of 3-(2-hydroxyphenyl)-4-amino-5-mercapto-1,2,4-triazole with 2-bromo-4-nitroacetophenone. The compound was characterized by means of elemental analysis, IR, H-1 NMR, C-13 NMR, mass spectrometry, and X-ray diffraction. The compound crystallizes in a monoclinic system with space group C-c, alpha=2.1853(4) nm, b=2.1192(5) nm, c=1.3526(3) nm, beta=95.21(2)degrees, V=6.238(2) nm(3), D-calcd=1.505 Mg/m(3), Z=16, F(000)=2916, R,=0.0501, omegaR(2)=0.0427. A comparison between the crystal structures of 1,2,4-triazolo[3,4-b] [1,3,4] thiadiazine and 1,2,4-triazolo[3,4-b][1,3,4] thiadiazole was made in the structural view. A two-dimensional network is formed by hydrogen bonds and pi-pi stacking interactions.