Transannular and intermolecular interactions between chalcogen atoms: syntheses and properties of dichalcogena dications and trichalcogena hypervalent dications

Intramolecular (transannular) and intermolecular through-space interactions between chalcogen atoms have been described. This account includes the following three topics. (1) Various types of bis-chalcogenides and their mono-oxides, which have the two chalcogen atoms in close proximity in a molecule, give the dichalcogena dications upon the oxidation with two equivalents of NOBF4 or treatment with one equivalent of triflic anhydride (Tf2O). The stability of the dichalcogena dications increases in the order S