Poly[[di-aqua-[μ-1,4-bis(pyridin-4-ylmeth-yl)piperazine-κ(2) N:N']{μ-2,2'-[(1,4-phenyl-ene)bis(-oxy)]di-acetato-κ(2) O:O'}cobalt(II)] penta-hydrate].

In the title compound, {[Co(C10H8O6)(C16H20N4)(H2O)2]·5H2O} n , octa-hedrally coordinated Co(II) ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydro-quinone-O,O'-di-acetate (hqda) anions {systematic name: 2,2'-[(1,4-phenyl-ene)bis-(-oxy)]di-acetate}, two trans-pyridine N-donor atoms from two bis-(pyridin-4-ylmeth-yl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H2O)2] n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O-H⋯O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water mol-ecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the crystal data take the presence of these mol-ecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement.