On the basis of our results, which concern sp3N⋯Br–Rf [Rf = per(poly)fluoroalkyl], sp3O⋯I–Rf, sp2O⋯I–Rf, sp3N⋯I–Rf, sp2N⋯I–Rf and interactions of sp2N⋯I–Rf with different substituents, a brief profile of the interactions between electronegative atoms (N, O, S) and halogen atoms (I, Br) of fluorine-containing alkylates is determined. The first example of an aliphatic fluorine-containing donor-acceptor supramolecule that is based on the N⋯Br–Rf interaction is reported in this paper. Our X-ray structure shows that 1,2-dibromotetrafluoroethane and 1,4-dimethylpiperazine alternately form endless chains depending on the N⋯Br–Rf interactions. The distance between Br and N is 2.864(3)
Å, which is considerably longer than the average covalent bond between N and Br, but it is also definitively shorter than the sum of the corresponding van der Waals radii of N and Br. From two other crystals, we successfully obtained precise data on the sp3O⋯X–Rf and sp2O⋯X–Rf interactions. Furthermore, an investigation of the substituent group effect is presented. We also report a valuable method to recrystallize and collect X-ray data of co-crystals that are easily disordered.
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