Structural characterization of unusually stable polycyclic ozonides

• Compound 3 crystallizes in the unusual space group R3¯m.
• Most ozonides crystallize in the monoclinic system with P21/c space group as racemic crystal.
• Compound 3 space group represents only ∼0.04% of small-molecule crystal structures.
• X-ray crystallographic studies of stable polycyclic ozonides were carried out.

The single crystal structure of seven tri- and tetracyclic ozonides derived from 8-oxabicycle[3.2.1]oct-6-en-3-ones have been characterized by X-ray diffraction method. Five ozonides (4, 5, 6, 7 and 8) crystallize in the monoclinic crystal system with P21/c space group. Compound 3 crystallize in the unusual centrosymmetric space group R3¯m, which represents ∼0.04% of the total number of structures know. The supramolecular structure of 3 forms infinite channels in a hexagram fashion, resulting in a honeycomb-like structure. Semi-empirical (PM6) and density functional theory methods (DFT) with the B3LYP functional and the 6-31G(d) basis set were used to optimize the geometries and compute structural parameters (bond lengths, angles and dihedral angles) that could be compared to the refined crystal structure. The theoretical results show good agreements with the experimental structure.

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