Synthesis and crystal structure of a 6-chloro­nicotinate salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4′-bi­pyridine

A 6-chloro­nicotinate (6-Clnic) salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4′-bi­pyridine (4,4′-bpy), namely, catena-poly[[[tetra­aqua­nickel(II)]-μ-4,4′-bi­pyridine-κ(2) N:N′] bis­(6-chloro­nicotinate) tetra­hydrate], {[Ni(C(10)H(8)N(2))(H(2)O)(4)](C(6)H(3)ClNO(2))(2)·4H(2)O}(n) or {[Ni(4,4′-bpy)(H(2)O)(4)](6-Clnic)(2)·4H(2)O}(n), (1), was prepared by the reaction of nickel(II) sulfate hepta­hydrate, 6-chloro­nicotinic acid and 4,4′-bi­pyridine in a mixture of water and ethanol. The mol­ecular structure of 1 comprises a one-dimensional polymeric {[Ni(4,4′-bpy)(H(2)O)(4)](2+)}(n) cation, two 6-chloro­nicotinate anions and four water mol­ecules of crystallization per repeating polymeric unit. The nickel(II) ion in the polymeric cation is octa­hedrally coordinated by four water mol­ecule O atoms and by two 4,4′-bi­pyridine N atoms in the trans position. The 4,4′-bi­pyridine ligands act as bridges and, thus, connect the symmetry-related nickel(II) ions into an infinite one-dimensional polymeric chain extending along the b-axis direction. In the extended structure of 1, the polymeric chains of {[Ni(4,4′-bpy)(H(2)O)(4)](2+)}(n), the 6-chloro­nicotinate anions and the water mol­ecules of crystallization are assembled into an infinite three-dimensional hydrogen-bonded network via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of the representative hydrogen-bonded ring motifs: tetra­meric R (2) (4)(8) and R (4) (4)(10) loops, a dimeric R (2) (2)(8) loop and a penta­meric R (4) (5)(16) loop.