Structure, basicity, and thermodynamic properties of 3,5-bis(trifluoromethyl)-1,2,4-triazole with regard to 1,2,4-triazole : the trifluoromethylation effect

Thermodynamic properties (enthalpies of sublimation, gas-phase basicity) of 3,5-bis(trifluoromethyl)- 1,2,4-triazole have been measured. These properties are discussed in the larger framework of two other triazoles, the parent compound and 3(5)-(trifluoromethyl)-1,2,4-triazole, thanks to ab initio calculations at the MP2/6-31G * //6-31G * level of accuracy. The calculations provide (i) an excellent description of the vibrational frequencies of 1H-1,2,4-triazole; (ii) a geometry for this compound more consistent with the microwave results; (iii) a description of the trifluoromethyl group as a substituent in the azole series; (iv) an excellent accord with the experimental proton affinity, and (v) an understanding of the interesting properties of the title compound