Synthetic and structural investigations of bis(N-alkyl-benzoselenadiazolium) cations.

The synthesis, and spectroscopic and structural characterization of bridged dicationic derivatives of benzo-2,1,3-selenadiazoles are reported. The chloride salt of [H4C6NSeN–CH2–CH2–NSeNC6H4]2+ crystallizes forming a macrocyclic structure in which two cations are bridged by Se⋯Cl chalcogen bonds (ChBs), with a third chloride at the centre of the macrocycle. The structure of [1,2-(H4C6NSeN)2-C6H10]Cl2 consists of two selenadiazolium cations linked by a chiral cyclohexane and capped by Se⋯Cl ChBs. Tetrafluoroborate salts of a xylene bridge crystallize in two pseudopolymorphs in which the cations form Se⋯F ChBs in an anti- or syn-conformation. The triflate salt of ethylene-bridged cations dimerizes through the formation of the [Se–N]2 supramolecular synthon with Se⋯O ChBs capping the second selenium atom. In contrast, [H4C6NSeN–CH2–CH2–CH2–NSeNC6H4](CF3SO3)2 only forms Se⋯O ChBs. [ABSTRACT FROM AUTHOR]