Polymorphism and Hirshfeld surface analysis of tetra­oxa[2]perfluoro­arene[2]triazine

Abstract

Tetra­oxa[2]perfluoro­arene[2]triazine (C₂₀H₆F₈N₆O₆), composed of two tetra­fluoro­phenyl­ene and two triazine moieties connected by four oxygen atoms, was crystallized via slow evaporation of a di­chloro­methane solution, yielding two polymorphs with block- and plate-shaped crystals.

The title compound, tetra­oxa[2]perfluoro­arene[2]triazine (C₂₀H₆F₈N₆O₆), composed of two tetra­fluoro­phenyl­ene and two triazine moieties connected by four oxygen atoms, was crystallized via slow evaporation of a di­chloro­methane solution, yielding two polymorphs: block- (I) and plate-shaped (II) crystals. Polymorph I (triclinic, P1, V = 516 ų at 173 K) was previously reported by Yang et al. [(2015. Org. Lett.15, 4414–4417] whereas the newly identified polymorph II (triclinic, P1, V = 1085 ų at 100 K) shares the same space group but has a unit-cell volume twice as large, accommodating two symmetrically distinct mol­ecules, Mol­ecule-1 and Mol­ecule-2, with a different mol­ecular arrangement. Since these crystals are expected to exhibit the characteristics of non-porous adaptive crystals, detailed analyses of inter­molecular inter­actions were conducted, revealing that C—F⋯π-hole inter­actions are more pronounced in II than in I. Hirshfeld surface analysis at 100 K revealed that the primary contributions to the crystal packing in polymorph I were F⋯F (17.1%), F⋯H/H⋯F (21.5%), C⋯H/H⋯C (6.3%), C⋯F/F⋯C (4.5%) and C⋯O/O⋯C (9.2%) inter­actions, whereas in polymorph II, these inter­actions were F⋯F (9.9% and 10.0%), F⋯H/H⋯F (20.9% and 26.5%), C⋯H/H⋯C (6.3% and 2.9%), C⋯F/F⋯C (8.5% and 10.0%) and C⋯O/O⋯C (4.9% and 4.6%) for Mol­ecule-1 and Mol­ecule-2, respectively. Powder X-ray diffraction analysis indicates that polymorph I is the more stable crystalline form, predominantly obtained through rapid precipitation or by grinding the crystals.