Synthesis and crystal structure of poly[(3-amino-1,2,4-triazole)(μ3-1H-benzimidazole-5,6-dicarboxylato)cobalt(II)]

Abstract

The asymmetric unit of the title coordination polymer, [Co(C9H4N2O4)(C2H4N4)] n or [Co(L 1)(L 2)] n , consists of one crystallographically independent Co2+ centre, one L 1 2− ligand and one L 2 ligand (L 1 = 1H-benzimidazole-5,6-dicarboxylic acid, L 2 = 3-amino-1,2,4-triazole). The Co2+ centre is coordinated by two carboxylato-O atoms from two independent L 1 2− ligands and two nitrogen atoms from L 2 and another L 1 ligand. Thus, the metal center adopts a four-coordinate mode, forming a tetrahedral geometry. Interestingly, through the combination of two L 1 2−, two L 2 ligands and two Co2+ ions, a basic repeating unit is constructed, resulting in the formation of a one-dimensional straight chain structure. These chains are further expanded to the final three-dimensional framework via N—H...O hydrogen-bonding interactions.