Effect of Aromatic System Expansion on Crystal Structures of 1,2,5-Thia- and 1,2,5-Selenadiazoles and Their Quaternary Salts: Synthesis, Structure, and Spectroscopic Properties

Abstract

Rational manipulation of secondary bonding interactions is a crucial factor in the construction of new chalcogenadiazole-based materials. This article reports detailed experimental studies on phenanthro[9,10-c][1,2,5]chalcogenadiazolium and 2,1,3-benzochalcogenadiazolium salts and their precursors. The compounds were synthesized, characterized employing NMR and UV-Vis spectroscopy. TD-DFT calculations were also performed. The influence of the size of the aromatic system on the molecular motifs formed by the compounds in the solid state has been studied by means of single-crystal X-ray diffraction. In case of the salts, the nature of an anion was also taken into consideration. The results show that cyclic [E···N]2 supramolecular synthon connects neighboring molecules of phenanthro[9,10-c][1,2,5]chalcogenadiazoles, with a relatively large aromatic system, in dimers regardless of the chalcogen atom in the molecule. Both N-methyl-2,1,3-benzothiadiazolium and N-methylphenanthro[9,10-c][1,2,5]chalcogenadiazolium cations have a strong affinity for triflate and iodide anions, therefore the formation of S···N or Se···N secondary bonding interactions is observed only in two out of the eight quaternary salts. Less coordinating anions must be used to enable the building blocks studied to form cyclic [E···N]2 synthons. Moreover, for two of the triflate salts, which are isostructural, a new supramolecular motif has been observed.

Adducts of 2-Pyridylselenenyl Halides and Nitriles as Novel Supramolecular Building Blocks: Four-Center Se···N Chalcogen Bonding versus Other Weak Interactions

“…A similar Ch–N (Ch = S, Se, Te) structural motif is present in relative chalcogenadiazoles (Scheme ), which are important supramolecular building blocks which were extensively described in numerous reviews and research articles. ,,− …”

Exploring Supramolecular Assembly Space of Cationic 1,2,4-Selenodiazoles: Effect of the Substituent at the Carbon Atom and Anions

“…[ 13 , 14 , 15 , 16 ]. Chalcogenodiazoles have gained particular interest within ChB research and have been extensively studied in recent years in the context of their applications in anion recognition and as supramolecular building blocks [ 6 , 17 , 18 , 19 , 20 , 21 ].…”

Robust Supramolecular Dimers Derived from Benzylic-Substituted 1,2,4-Selenodiazolium Salts Featuring Selenium⋯π Chalcogen Bonding

“…In this context, chalcogenodiazoles represent attractive objects for the creation of such materials [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. They were shown to be capable of forming symmetrical antiparallel supramolecular dimers via two Se⋯N ChB interactions.…”

“…They were shown to be capable of forming symmetrical antiparallel supramolecular dimers via two Se⋯N ChB interactions. These important supramolecular synthons were intensively studied in the last years [ 33 , 34 , 35 , 36 , 37 , 38 ].…”