Herein, we present a complete crystallographic study of three series of N1-aryl substituted-2-pyrazolines, the aryl group being 4-nitrophenyl (series 1), 2,4-dinitrophenyl (series 2), and 2,4,6-trinitrophenyl (series 3). The structural features, bond distances and angles as well as torsions for each single compound will be described and comparatively discussed with data for related heterocycles found in the Cambridge Structural Database (2020.2.0). A deeper look at the data has been achieved to know the influence of the substituents on the molecular structures. In the crystals of compounds with stereogenic centers at positions 4 and 5, the presence of both enantiomers has been encountered in 12 cases out of 14 that include a literature result. Finally, molecular packings in all series have been analyzed reaching the conclusion that they follow several patterns depending on the existence or not, and the type of intermolecular interactions. A general pattern has been observed which implies a certain tendency of the molecules to arrange into chains, whose additional contacts could extend the dimensionality of the network.

This work was carried out with financial support from the Ministerio de Ciencia, Innovación y Universidades (Projects CTQ2017-84825-R, PGC2018-094644-B-C2). Thanks are given to Dr. Patricia Delgado and Dr. Emilio Matesanz of CAI Difracción de Rayos X, Universidad Complutense de Madrid, for technical assistance