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

Abstract

Chalcogenodiazoles have been intensively studied in recent years in the context of their supramolecular chemistry. In contrast, the newly discovered cationic 1,2,4-selenodiazole supramolecular building blocks, which can be obtained via coupling between 2-pyridylselenyl halides and nitriles, are virtually unexplored. A significant advantage of the latter is their facile structural tunability via the variation of nitriles, which could allow a fine tuning of their self-assembly in the solid state. Here, we explore the influence of the substituent (which derives from the nitrile) and counterions on the supramolecular assembly of cationic 1,2,4-selenodiazoles via chalcogen bonding.

Towards Anion Recognition and Precipitation with Water-Soluble 1,2,4-Selenodiazolium Salts: Combined Structural and Theoretical Study

“…The formation of similar 2Se–2N squares was observed earlier for the adducts of PySeCl 2 with acetonitrile and trichloroacetonitrile. In contrast, the adduct of 2 with hexanenitrile formed supramolecular polymers via Se⋯Cl and H⋯Cl interactions [ 18 ]. Thus, the replacement of chloride by TFA in pentyl-substituted 1,2,4-selenodiazolium salt had a dramatic impact on the self-organization of the compound in the solid state.…”

“…Moreover, 1,2,4-selenodiazolium cations bind halide anions via a combination of ChB and HB. The latter supramolecular structural motif was observed for all structurally characterized selenodiazolium halides derived from 2-pyridylselenyl halides and nitriles [ 15 , 16 , 17 , 18 ]. However, currently, there is no data about binding modes and energies of 1,2,4-selenodiazoliums with other anions.…”

Noncovalent Interactions and Crystal Structure Prediction of Energetic Materials

“…Reduced density gradient (RDG) is powerful to reveal the noncovalent interaction (NCI) [32][33][34]. RDG is defined as follows:…”

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

“…Recently, we described the synthesis of cationic 1,2,4-selenodiazolium salts via unprecedented cyclization between bifunctional 2-pyridylselenyl reagents and nitriles [ 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. The latter new heterocycles also showed a potency to form Se 2 N 2 supramolecular dimers in some instances.…”

“…The latter new heterocycles also showed a potency to form Se 2 N 2 supramolecular dimers in some instances. However, for some of them, Se 2 N 2 dimers formation was not observed when other weak noncovalent forces outcompeted the squares formation [ 41 , 42 , 43 ]. These stimulated us to search for the strategies to reliably form Se 2 N 2 synthons.…”