Chalcogen S Center Dot Center Dot Center Dot S Bonding In Supramolecular Assemblies Of Cadmium(Ii) Coordination Polymers With Pyridine-Based Ligands

Two cadmium(II) coordination polymers, with thiocyanate and pyridine-based ligands e.g., 3-acetamidopyridine (3-Acpy) and niazid (nicotinic acid hydrazide, nia), namely one-dimensional {[Cd(SCN)(2)(3-Acpy)]}(n) (1) and two-dimensional {[Cd(SCN)(2)(nia)]}(n) (2), are prepared in the mixture of water and ethanol. The adjacent cadmium(II) ions in 1 are bridged by two N,S-thiocyanate ions and an N,O-bridging 3-Acpy molecule, forming infinite one-dimensional polymeric chains, which are assembled by the intermolecular N-H center dot center dot center dot S hydrogen bonds in one direction and by the intermolecular S center dot center dot center dot S chalcogen bonds in another direction. Within the coordination network of 2, the adjacent cadmium(II) ions are bridged by N,S-thiocyanate ions in one direction and by N,O,N'-chelating and bridging nia molecules in another direction. The coordination networks of 2 are assembled by the intermolecular N-H center dot center dot center dot S and N-H center dot center dot center dot N hydrogen bonds and S center dot center dot center dot S chalcogen bonds. Being the only supramolecular interactions responsible for assembling the polymer chains of 1 in the particular direction, the chalcogen S center dot center dot center dot S bonds are more significant in the structure of 1, whilst the chalcogen S center dot center dot center dot S bonds which act in cooperation with the N-H center dot center dot center dot S and N-H center dot center dot center dot N hydrogen bonds are of less significance in the structure of 2.