Synergistic Interplay between Intermolecular Halogen and Chalcogen Bonds in the Dihalogen Adducts of 2,5-Bis(pyridine-2-yl)tellurophene: Reactivity Insights and Structural Trends.

The reactivity of 2,5-bis(pyridine-2-yl)tellurophene (L) toward elemental dihalogens XY (X = Y = I, Br; X = I, Y = Cl, Br) was explored. The oxidative addition of the dihalogen molecules to the Te(II) center was observed in LI2 (1), LI2·1/2I2 (2), LBr2 (3), LBr1.63I0.37 (4), and LCl1.86I0.14 (5), which were characterized in the solid state by X-ray diffraction analysis and Raman spectroscopy. In all cases, a seesaw geometry at the chalcogen atom was observed with the linear X-Te-X moiety almost perpendicular to the tellurophene ring. The crystal packing in these compounds displays a peculiar and synergistic interplay of halogen and chalcogen bonds. A comparison with analogous compounds reported in the literature was carried out to establish the key factors determining the supramolecular arrays of noncovalent intermolecular interactions (NCIs) observed in this class of compounds.