3,6-bis(4-nitrophenyl)-5,6-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (en)1,2,4-triazolo[3,4-b][1,3,4]thiadiazole, 5,6-dihydro-3,6-bis(4-nitrophenyl)- (en)