2-Pyridylselenenyl versus 2-Pyridyltellurenyl Halides: Symmetrical Chalcogen Bonding in the Solid State and Reactivity towards Nitriles

Abstract

The synthesis of 2-pyridyltellurenyl bromide via Br2 oxidative cleavage of the Te–Te bond of dipyridylditelluride is reported. Single-crystal X-ray diffraction analysis of 2-pyridyltellurenyl bromide demonstrated that the Te atom of 2-pyridyltellurenyl bromide was involved in four different noncovalent contacts: Te⋯Te interactions, two Te⋯Br ChB, and one Te⋯N ChB contact forming 3D supramolecular symmetrical framework. In contrast to 2-pyridylselenenyl halides, the Te congener does not react with nitriles furnishing cyclization products. 2-Pyridylselenenyl chloride was demonstrated to easily form the corresponding adduct with benzonitrile. The cyclization product was studied by the single-crystal X-ray diffraction analysis, which revealed that in contrast to earlier studied cationic 1,2,4-selenadiazoles, here we observed that the adduct with benzonitrile formed supramolecular dimers via Se⋯Se interactions in the solid state, which were never observed before for 1,2,4-selenadiazoles.

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

“…), zero or very close to zero energy density (0.000–0.002 a.u.) in these bond critical points (3, –1), and estimated strength for appropriate short contacts (0.9–5.0 kcal/mol) are typical for weak hydrogen bonds [ 3 , 4 , 36 ] and non-covalent interactions involving halogen [ 8 , 9 , 10 , 11 , 12 , 32 , 37 , 38 ] and chalcogen [ 22 , 23 , 39 , 40 , 41 , 42 ] atoms in similar chemical systems. The strongest non-covalent interactions in the studied model supramolecular associates 3 – 10 were chalcogen bonds: Se1···Cl24 in 3 (4.7 kcal/mol), Se1···Cl30 in 4 (4.4 kcal/mol), Se1···Cl38 in 5 (5.0 kcal/mol), Se1···Cl24 in 6 (3.5 kcal/mol), Se29···Cl56 in 7 (5.0 kcal/mol), Se1···Br15 in 8 (3.5 kcal/mol), Se2···C31 in 9 (1.3 kcal/mol), and Se1···F29 (4.7 kcal/mol) in 10 .…”

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

“…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.…”

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.…”