Structural investigation and Hirshfeld surface analysis of three organic picrate salts

Abstract

Abstract Three picrate salt crystals, namely 5-amino-6-methylquinolin-1-ium 2,4,6-trinitrophenolate (I), 3-phenyl-1H-pyrazol-2-ium 2,4,6-trinitrophenolate (II) and 1H-imidazol-3-ium 2,4,6-trinitrophenolate (III) were characterized by X-ray diffraction. Salt I crystallizes in space group of P21/c, with a=15.096(2), b=7.2864(9), c=15.248(2) Å, β=98.437(2)°, V=1659.1 Å3 and Z=4. Salt II crystallizes in monoclinic space group P21/c, with a=13.6230(9), b=6.7421(5), c=17.7508(12) Å, β=106.001(1)°, V=1567.20 Å3 and Z=4. Whereas salt III crystallizes in triclinic system, space group P1̅, with a=7.6919(10), b=7.9218(10), c=10.2230(13) Å, α=81.909(2), β=77.985(2), γ=82.629(2)°, V=600.05 Å3 and Z=2. Protons were transferred from the picric acids to their corresponding bases, forming intermolecular N+–H···O− hydrogen bonds in the three salts. Salts I and II form planes, whereas salt III forms chains via N–H···O and C–H···O hydrogen bonds as their supramolecular assembly. Planes and chains in all these salts were interconnected through π···π interaction. The intermolecular interactions in the crystal structures were quantified and were analysed using Hirshfeld surface analysis.