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

The asymmetric unit of the title coordination polymer, [Co(C(9)H(4)N(2)O(4))(C(2)H(4)N(4))](n) or [Co(L (1))(L (2))](n), consists of one crystallographically independent Co(2+) 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 Co(2+) 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 Co(2+) 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.