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

Abstract

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-κ2N:N′] bis(6-chloronicotinate) tetrahydrate], {[Ni(C10H8N2)(H2O)4](C6H3ClNO2)2·4H2O}nor {[Ni(4,4′-bpy)(H2O)4](6-Clnic)2·4H2O}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 of1comprises a one-dimensional polymeric {[Ni(4,4′-bpy)(H2O)4]2+}ncation, 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 thetransposition. 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 theb-axis direction. In the extended structure of1, the polymeric chains of {[Ni(4,4′-bpy)(H2O)4]2+}n, the 6-chloronicotinate anions and the water molecules of crystallization are assembled into an infinite three-dimensional hydrogen-bonded networkviastrong O—H...O and O—H...N hydrogen bonds, leading to the formation of the representative hydrogen-bonded ring motifs: tetramericR24(8) andR44(10) loops, a dimericR22(8) loop and a pentamericR45(16) loop.