Crystal structure of catena-poly[bis(formato-κO)bis­[μ(2)-1,1′-(1,4-phenyl­ene)bis­(1H-imidazole)-κ(2) N (3):N (3′)]cobalt(II)]

A red block-shaped crystal of the title compound, [Co(HCOO)(2)(C(12)H(10)N(4))(2)](n), was obtained by the reaction of cobalt(II) nitrate hexa­hydrate, formic acid and 1,1′-(1,4-phenyl­ene)bis­(1H-imidazole) (bib) mol­ecules. The asymmetric unit consists of one Co(II) cation, one formate ligand and two halves of a bib ligand. The central Co(II) cation, located on an inversion centre, is coordinated by two carboxyl­ate O atoms and four N atoms from bib ligands, completing an octa­hedral coordination geometry. The Co(II) centres are bridged by bib ligands, giving a two-dimensional net. Topologically, taking the Co(II) atoms as nodes and the bib ligands as linkers, the two-dimensional structure can be simplified as a typical sql/Shubnikov tetra­gonal plane network. The structure features C—H⋯O hydrogen-bonding inter­actions between formate and bib ligands, resulting in a three-dimensional supra­molecular network.