Structural diversity of supramolecular networks composed of 2,1,3-chalcogenadiazole silver(i) complexes: the role of chalcogen bonding in molecular self–assembly

Abstract

Several new coordination compounds of 2,1,3-chalcogenadiazoles with AgNO₃, AgClO₄, AgBF₄ and AgSbF₆ were prepared and structurally characterized. The observed structural diversity of the AgNO₃ complexes results from a variation of the coordination mode of the NO₃⁻ unit and substitution pattern of the chalcogenadiazole ligands. Particularly the steric effect of the bulky substituent at C-4 of the chalcogenadiazole unit causes coordination to the silver cation of only one nitrogen atom, whereas the second N atom engages in [Se⋯N]₂ interaction creating a 1D supramolecular polymer. The ligands without bulky substituents coordinate two silver ions from both sides of the molecule, in μ₂-bridging mode, creating polymeric chain structures. In contrast, the structure of the complexes with poorly coordinating anions (ClO₄⁻, BF₄⁻ and SbF₆⁻) is almost not affected by substituents and in all cases each silver cation coordinates two ligand molecules, whereas the self-complementary [Se⋯N]₂ interactions between the ligand molecules create 1D supramolecular polymeric structures. In some cases, solvent molecules enter the coordination sphere of the metal.