Energetic and structural properties of 4-nitro-2,1,3-benzothiadiazole

The energetic study of 4-nitro-2,1,3-benzothiadiazole has been developed using experimental techniques together with computational approaches. The standard (p degrees = 0.1 MPa) molar enthalpy of formation of crystalline 4-nitro-2,1,3-benzothiadiazole (181.9 +/- 2.3 kJ . mol(-1)) was determined from the experimental standard molar energy of combustion -(3574.3 +/- 1.3) kJ . mol(-1), in oxygen, measured by rotating-bomb combustion calorimetry at T = 298.15 K. The standard (p degrees = 0.1 MPa) molar enthalpy of sublimation, at T = 298.15 K, (101.8 +/- 4.3) kJ . mol(-1), was determined by a direct method, using the vacuum drop micro-calorimetric technique. From the latter value and from the enthalpy of formation of the solid, it was calculated the standard (p degrees = 0.1 MPa) enthalpy of formation of gaseous 4-nitro-2,1,3-benzothiadiazole as (283.7 +/- 4.9) kJ . mol(-1). Standard ab initio molecular orbital calculations were performed using the G3(MP2)//B3LYP composite procedure and several working reactions in order to derive the standard molar enthalpy of formation 4-nitro-2,1,3-benzothiadiazole. The ab initio results are in good agreement with the experimental data. (C) 2012 Elsevier Ltd. All rights reserved.