catena-Poly[[aquanickel(II)]-μ-pyridine-2,6-dicarboxylato-[aquanickel(II)]-μ-2,5-di-4-pyridyl-1,3,4-thiadiazole]

The two independent Ni(II) ions in the one-dimensional title complex, [Ni(2)(C(7)H(3)NO(4))(2)(C(12)H(8)N(4)S)(H(2)O)(2)](n) or [Ni(2)(pydc)(2)(bpt)(H(2)O)(2)](n) (H(2)pydc = pyridine-2,6-dicarboxylic acid and bpt = 2,5-di-4-pyrid-yl-1,3,4-thia-diazole), have different coordination environments. One Ni(II) ion is in a slightly-distorted octa-hedral coordination environment formed by three O atoms from two adjacent pydc ligands, two N atoms from bpt and pydc ligands, and one water mol-ecule, while the other Ni(II) ion is in distorted square-pyramidal geometry, coordinated by two O atoms from two carboxyl-ate groups and two N atoms from the pyridine rings of the pydc and bpt ligands in the basal plane, while a coordinated water mol-ecule occupies the apical site. In the crystal structure, the H atoms of both water mol-ecules are involved in inter-molecular hydrogen bonds with the O atoms of uncoordinated carboxyl-ate groups, which link chains into a three-dimensional network.