X-ray reflections for compound A (Form I, Form II and Form III) and compound B were collected on an Oxford Xcalibur Gemini Eos CCD diffractometer at 298 K using Cu Kα radiation (λ = 1.54184 Å) and data reduction was performed using CrysAlisPro (CrysAlis CCD and CrysAlis RED; Oxford Diffraction, 2008 ▸) and OLEX2 (Dolomanov et al., 2009 ▸) to solve and refine the crystal structure. X-ray reflections for compound C were collected on a Bruker D8 Quest CCD diffractometer equipped with a graphite monochromator and Mo Kα fine-focus sealed tube (λ = 0.71073 Å), and high-temperature Form IV (Compound A) was collected on Bruker D8 venture diffractometer at 180°C; reduction was performed using APEXII Software (Bruker, 2000 ▸). Intensities were corrected for absorption using SADABS (Sheldrick, 1997 ▸) and the structure was solved and refined using SHELX97 (Sheldrick, 1997 ▸). All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on hetero atoms were located from difference electron-density maps and all C—H H atoms were fixed geometrically. Hydrogen-bond geometries were determined in PLATON (Spek, 2002 ▸). X-Seed (Barbour, 1999 ▸) was used to prepare packing diagrams. Crystal structures are deposited as part of the supporting information and may be accessed at https://www.ccdc.cam.ac.uk/structures/ (CCDC Nos. 1488992–1488996).