Syntheses, supramolecular networks and Hirshfeld surface and thermal analyses of two new cadmium chloride coordination polymers with an N,O-chelating ligand.

Two new coordination polymers, namely poly[[(3-aminopyrazin-4-ium-2-carboxylate-κ2N1,O)di-μ-chlorido-cadmium(II)] monohydrate], {[CdCl2(C5H5N3O2)]·H2O}n, (1), and poly[2-amino-3-carboxypyrazin-1-ium [(3-aminopyrazine-2-carboxylato-κ2N1,O)di-μ-chlorido-cadmium(II)] monohydrate], {(C5H6N3O2)[Cd(C5H4N3O2)Cl2]·H2O}n, (2), have been synthesized from the reaction of cadmium(II) chloride and 3-aminopyrazine-2-carboxylic acid (Hapca) under mild conditions in acidic media. The two coordination polymers have been characterized by single-crystal X-ray diffraction and show chloride-bridged zigzag chains with octahedrally coordinated metal ions, where Hapca acts as a bidentate ligand via the π-conjugated N atom and a carboxylate O atom. The chains are further interconnected via noncovalent interactions into three-dimensional supramolecular networks. The dominant H...O and H...Cl interactions for both compounds were quantified using Hirshfeld surface analysis. The thermal stability and topological analysis of the two-dimensional networks of (1) and (2) are also discussed.