Influence of the anion base X (X=F−, Cl−, Br−, NO3− and SO42−) on the formation of Chalcogen bonds in Chalcogenodiazoles C4N4Ch (Ch=S, Se and Te)

• Based on CSD search, chalcogen bonds can be composed of C 4 N 4 Ch (Ch=S, Se, Te) and anions. • The strongest chalcogen bond was formed between SO 4 2 − and C 4 N 4 Te • monomers. • These studied chalcogen bonds are dominated by electrostatic interaction. • Double chalcogen bond was confirmed to exist in these studied complexes. In recent years, due to the high directionality and adjustable strength, chalcogen bonds have attracted extensive attention from both crystal engineering and theoretical perspectives. A search of the Cambridge Structural Database (CSD) has revealed a large number of crystal structures containing chalcogen group elements and anions. On this basis, some typical structures containing chalcogen group elements C 4 N 4 Ch (Ch=S, Se and Te) and anions X (X= F − , C l − , B r − , NO 3 − and SO 4 2 − ) were chosen to form the Ch ⋯ X chalcogen bond. The properties of these chalcogen bonds are analyzed in detail, including bond lengths, interaction energies, charge transfer, electron densities and energy decomposition analyses. The results show that these studied Ch ⋯ X chalcogen bonds dominated by electrostatic interactions have large interaction energy, reaching a maximum of 97.41 kcal/mol in the case of C 4 N 4 Te ⋯ SO 4 2 − complex. Interestingly, the double chalcogen bond is found in these studied C 4 N 4 Ch ⋯ X complexes. The chalcogen bond Ch…X is formed by Lewis acid C 4 N 4 Ch (Ch=S, Se and Te) molecular and Lewis base anion X (X= F − , C l − , B r − , NO 3 − and SO 4 2 − ), especially the structure of C 4 N 4 Te and C 4 N 4 Te…F exist in crystal database. The versatility and formation of chalcogen bond in C 4 N 4 Ch…X complexes are analyzed at MP2/aug-cc-pVTZ(PP) theory level. The research shows that the Lewis base anion X can form relatively strong chalcogen bonds, and the nature of these studied chalcogen bond is electrostatic interaction. Interestingly, double chalcogen bond are found in C 4 N 4 Ch…X complexes.