Synthesis and crystal structure of a 6-chloro-nicotinate salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4'-bi-pyridine.

A 6-chloro-nicotinate (6-Clnic) salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4'-bi-pyridine (4,4'-bpy), namely, -poly[[[tetra-aqua-nickel(II)]-μ-4,4'-bi-pyridine-κ :'] bis-(6-chloro-nicotinate) tetra-hydrate], {Ni(CHN)(HO)·4HO} or {Ni(4,4'-bpy)(HO)·4HO} , (), was prepared by the reaction of nickel(II) sulfate hepta-hydrate, 6-chloro-nicotinic acid and 4,4'-bi-pyridine in a mixture of water and ethanol. The mol-ecular structure of comprises a one-dimensional polymeric {[Ni(4,4'-bpy)(HO)]} cation, two 6-chloro-nicotinate anions and four water mol-ecules of crystallization per repeating polymeric unit. The nickel(II) ion in the polymeric cation is octa-hedrally coordinated by four water mol-ecule O atoms and by two 4,4'-bi-pyridine N atoms in the position. The 4,4'-bi-pyridine ligands act as bridges and, thus, connect the symmetry-related nickel(II) ions into an infinite one-dimensional polymeric chain extending along the axis direction. In the extended structure of , the polymeric chains of {[Ni(4,4'-bpy)(HO)]} , the 6-chloro-nicotinate anions and the water mol-ecules of crystallization are assembled into an infinite three-dimensional hydrogen-bonded network strong O-H⋯O and O-H⋯N hydrogen bonds, leading to the formation of the representative hydrogen-bonded ring motifs: tetra-meric (8) and (10) loops, a dimeric (8) loop and a penta-meric (16) loop.