Poly[bis­(μ(2)-4,4′-bipyridine)bis­(3-nitro­benzoato)cobalt(II)]

The hydro­thermal reaction of cobalt nitrate with 4,4′-bipyridine and 3-nitro­benzoic acid lead to the formation of the title complex, [Co(C(7)H(4)NO(4))(2)(C(10)H(8)N(2))(2)](n). In the crystal structure, the Co(II) atoms are coordinated by two terminal carboxyl­ate anions and four 4,4′-bipyridine ligands within slightly distorted octa­hedra. 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 mol­ecule 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.