Poly[bis-(₂-4,4′-bipyridine)bis-(3-nitro-benzoato) cobalt(II)]

The hydro-thermal reaction of cobalt nitrate with 4,4′-bipyridine and 3-nitro-benzoic acid lead to the formation of the title complex, [Co(C ₇H₄NO₄)₂(C₁₀H ₈N₂)₂] n. In the crystal structure, the Co ^II atoms are coordinated by two terminal carboxyl-ate anions and four 4,4′-bipyridine ligands within slightly distorted octa-hedra. The Co ^II atom and one of the two independent 4,4′-bipyridine ligands are located on a twofold rotation axis, while the second independent 4,4′-bipyridine mol-ecule is located on a centre of inversion. One of the two rings of one 4,4′-bipyridine ligand is disordered over two orientations and was refined using a split model [occupancy ratio 0.68 (2):0.32 (2)]. The Co^II atoms are connected by the 4,4′-bipyridine ligands into layers, which are located parallel to the ab plane.