(Wiley, 2025-07-31) Claramunt, Rosa M.; Pérez Torralba, Marta; Elguero, José; Alkorta, Ibon
This publication presents the geometries of 157 nitro- and polynitropyrazoles. Among these, 109 compounds were theoretically studied using mainly the B3LYP/6–311++G(d,p) level of theory. Three-parameter Lee-Yang-Parr (B3LYP) is a density functional theory (DFT) method widely used in computational chemistry and constitutes an acceptable compromise for such a large set of compounds, some of them of considerable mass. The data set includes crystallographic parameters for 91 polynitropyrazoles; the remaining 67 compounds comprise 40 known and 27 newly reported structures. Several key issues are addressed: the investigation of 3,4-dinitro-1H-pyrazole, including nine X-ray structures (solvates and cocrystals); the prototropic tautomerism observed in four pairs of pyrazoles and the factors influencing the preference for a tautomer; the analysis of twelve 1-trinitromethyl-1H-pyrazoles; and a discussion of the detonation properties of 30 polynitro compounds. No previous work has included such a broad set of compounds. While comparing experimental data with theoretical calculations does not guarantee agreement in advance, in our case, the accordance regarding geometries is very good, except for some observed discrepancies. In the section on detonation properties, the consonance in terms of densities, planarity, and heats of formation is less strong but still sufficient to draw interesting conclusions.
