Novel Cationic 1,2,4-Selenadiazoles: Synthesis Via Addition Of 2-Pyridylselenyl Halides To Unactivated Nitriles, Structures And Four-Center Semidline Horizontal Ellipsisn Contacts

2-Pyridylselenyl halides undergo facile coupling with a triple CN bond of unactivated nitriles. Unprecedented heterocyclization allowed the preparation of a novel class of cationic 1,2,4-selenadiazoles in remarkably high yields. Cationic 1,2,4-selenadiazoles form supramolecular dimers in the crystal via SeMIDLINE HORIZONTAL ELLIPSISN chalcogen bonding, which was studied theoretically.