Poly[bis-(μ(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(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 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.