Poly[1,4-bis-(4-pyridylmeth-yl)piperazine-diium [[tetra-aqua-cobaltate(II)]-μ-pyromellitato-κO:O] dihydrate]

In the title compound, {(C(16)H(22)N(4))[Co(C(10)H(2)O(8))(H(2)O)(4)]·2H(2)O}(n), the octa-hedrally coordinated Co(II) atom is situated on an inversion center and possesses four aqua ligands. The Co atoms are linked into an anionic coordination polymer chain by bis-monodentate pyromellitate ligands. The chain motifs are connected into a supra-molecular layer by hydrogen bonding mediated by uncoordinated water mol-ecules. Charge balance is provided by doubly protonated bis-(4-pyridylmeth-yl)piperazine units, which are anchored to the coordination polymer chain motifs by N-H⋯O hydrogen bonding.