Design of Supramolecular Tectons via Intramolecular S/Se⋅⋅⋅ONO2 Chalcogen Bonding

Abstract

A series of 2‐nitrochalcogenocyanato(hetero)arenes were synthesized by the reaction of 2‐nitrohalo(hetero)arenes with potassium thio‐ or selenocyanate. These compounds were characterized by NMR spectroscopy, high‐resolution mass spectrometry, and X‐ray crystallography. In the obtained crystal structures, strong intramolecular Ch⋅⋅⋅O_NO2 (Ch=S, Se) chalcogen bonds between the chalcogen atom of the chalcogenocyanate moiety and the nitro group were revealed. These interactions prevent rotation of the nitro group, and thus stabilize the obtained 2‐nitrochalcogenocyanato(hetero)arenes in a distorted planar geometry. In addition, intermolecular Ch⋅⋅⋅N chalcogen bonds were observed in some structures. Both intra‐ and intermolecular interactions were studied using methods based on first‐principles and DFT approaches (e. g. QTAIM, IGMH, ELF, NBO). Two of the synthesized chalcogenocyanates namely, 4‐nitro‐5‐thiocyanatophthalonitrile (2a) and 4‐nitro‐5‐selenocyanatophthalonitrile (2b) were identified as promising supramolecular tectons for cocrystallizations with aromatic hydrocarbons, and four new cocrystals (2 a⋅PhMe, 2 a⋅o‐XylH, 2 a⋅p‐XylH, and 2 b⋅1.5(p‐XylH)) were obtained. X‐ray diffraction studies of these cocrystals demonstrated that in all cases molecules of the phthalonitrile (2 a or 2 b) and the corresponding hydrocarbon are packed into infinity columnar stacks via π⋅⋅⋅π interactions, whereas intermolecular Ch⋅⋅⋅O/N ChBs bound them to form the final supramolecular architecture.