Crystal Structure and Thermal Decomposition Kinetics of 3-Nitro-4-diazo-5-oxygenpyrazole

A novel compound 3-nitro-4-diazo-5-oxypyrazole was synthesized by the nitration of 4-amino-3,5-dinitropyrazole using nitrification agents of fuming nitric acid and trifluoroacetic anhydride. The compound was purified by column chromatography and characterized by IR, NMR, MS and elemental analysis. Two different single crystals obtained by culturing with ethyl acetate as a solvent were measured by X-ray single-crystal diffractometer. The molecular weight of C;HN;O;is 155.09 and the two crystals belong to monoclinic system, space groups P21/n and P21/c. For 1: a = 5.5007（2）, b = 9.0691（4）, c = 11.4158（4） ?, β = 92.710°, V = 568.85 ?;, Z = 4, Dc = 1.811 g/cm;, μ = 0.162 mm-1, F（000） = 312 and the final deviation factor is 0.0213. Crystals 1 and 2 have similar unit cell parameters, except that a = 10.1828（12）, b = 5.5925（6）, c = 10.5574（10） ? and β = 108.330（4）° in crystal 2. The thermal behavior of the compound was studied by TG-DSC and melting endothermic peak and decomposition exothermic peak are at 425.7 and 534.5 K in DSC curve. The activation energy and pre-exponential factor of the exothermic decomposition reaction of the title compound obtained by Kissinger method and Flynn-Wall-Ozawa method are 50.38 k J/mol, 4.59 × 1022 s;and 55.89 k J/mol.