Synthesis and Physico-Chemical Studies on New Iron, Cobalt, Nickel and Copper Complexes of Some Carboxylic Acids

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.