2-Pyridylselenenyl versus 2-Pyridyltellurenyl Halides: Symmetrical Chalcogen Bonding in the Solid State and Reactivity towards Nitriles

The synthesis of 2-pyridyltellurenyl bromide via Br-2 oxidative cleavage of the Te-Te bond of dipyridylditelluride is reported. Single-crystal X-ray diffraction analysis of 2-pyridyltellurenyl bromide demonstrated that the Te atom of 2-pyridyltellurenyl bromide was involved in four different noncovalent contacts: TeMIDLINE HORIZONTAL ELLIPSISTe interactions, two TeMIDLINE HORIZONTAL ELLIPSISBr ChB, and one TeMIDLINE HORIZONTAL ELLIPSISN ChB contact forming 3D supramolecular symmetrical framework. In contrast to 2-pyridylselenenyl halides, the Te congener does not react with nitriles furnishing cyclization products. 2-Pyridylselenenyl chloride was demonstrated to easily form the corresponding adduct with benzonitrile. The cyclization product was studied by the single-crystal X-ray diffraction analysis, which revealed that in contrast to earlier studied cationic 1,2,4-selenadiazoles, here we observed that the adduct with benzonitrile formed supramolecular dimers via SeMIDLINE HORIZONTAL ELLIPSISSe interactions in the solid state, which were never observed before for 1,2,4-selenadiazoles.

Automated summary

The synthesis of 2-pyridyltellurenyl bromide via Br-2 oxidative cleavage of the Te-Te bond of dipyridylditelluride is reported, and the single-crystal X-ray diffraction analysis revealed its molecular and supramolecular structures. In contrast to the selenium congener, the tellurium congener does not react with nitriles but easily forms adducts.