Self-assembly of supramolecular architectures based on polybromide anions: crystal structure of image [tppz = tetra(2-pyridyl)pyrazine]

The reaction between tetra(2-pyridyl)pyrazine (tppz) and molecular bromine afforded image, characterised by means of FT-Raman spectroscopy and single-crystal X-ray diffraction. The crystal structure showed that the final framework can be considered as being made up by the self-assembly of the building blocks (Br−, Br2, H4tppz4+), driven exclusively by non-covalent interactions. The nature and positions of FT-Raman peaks for the linear symmetric image ion were interpreted based on MP2/LanL2DZ calculations.