Crystal structure of a looped-chain Co(II) coordination polymer: catena-poly[[bis­(nitrato-κO)cobalt(II)]bis­[μ-bis­(pyridin-3-ylmeth­yl)sulfane-κ(2) N:N′]]

The asymmetric unit of the title compound, [Co(NO(3))(2)(C(12)H(12)N(2)S)(2)](n), contains a bis­(pyridin-3-ylmeth­yl)sulfane (L) ligand, an NO(3) (−) anion and half a Co(II) cation, which lies on an inversion centre. The Co(II) cation is six-coordinated, being bound to four pyridine N atoms from four symmetry-related L ligands. The remaining coordination sites are occupied by two O atoms from two symmetry-related nitrate anions in a monodentate manner. Thus, the Co(II) centre adopts a distorted octa­hedral geometry. Two symmetry-related L ligands are connected by two symmetry-related Co(II) cations, forming a 20-membered cyclic dimer, in which the Co(II) atoms are separated by 10.2922 (7) Å. The cyclic dimers are connected to each other by sharing Co(II) atoms, giving rise to the formation of an infinite looped chain propagating along the [101] direction. Inter­molecular C—H⋯π (H⋯ring centroid = 2.89 Å) inter­actions between one pair of corresponding L ligands and C—H⋯O hydrogen bonds between the L ligands and the nitrate anions occur in the looped chain. In the crystal, adjacent looped chains are connected by inter­molecular π–π stacking inter­actions [centroid-to-centroid distance = 3.8859 (14) Å] and C—H⋯π hydrogen bonds (H⋯ring centroid = 2.65 Å), leading to the formation of layers parallel to (101). These layers are further connected through C—H⋯O hydrogen bonds between the layers, resulting in the formation of a three-dimensional supra­molecular architecture.