Crystal structure of catena-poly[[[trans-bis(aceto­nitrile-κN)diaquacobalt(II)]-μ-pyrazine-κ(2) N:N′] dinitrate]

The central structural motif of the title coordination polymer, [Co(NO(3))(2)(C(4)H(4)N(2))(CH(3)CN)(2)(H(2)O)(2)](n), is a chain composed of Co(II) ions linked by bis-monodentate bridging pyrazine ligands through their N atoms. The Co(II) ion is located on an inversion center and is additionally coordinated by two O atoms of water mol­ecules and two N atoms of aceto­nitrile mol­ecules. The resultant N(4)O(2) coordination sphere is distorted octa­hedral. The linear cationic chains extend parallel to the a axis and are aligned into layers parallel to the ac plane. Nitrate anions are situated in the space between the Co(II) chains and form O—H⋯O hydrogen bonds with the coordinating water mol­ecules, leading to a three-dimensional network structure. Weak C—H⋯O hydrogen bonds are also present between pyrazine or aceto­nitrile mol­ecules and the nitrate anions.