Poly[[bis-[μ-1,4-bis-(3-pyridylmeth-yl)piperazine-κN:N']dichlorido-cadmium(II)] tetra-hydrate].

In the title compound, {[CdCl(2)(C(16)H(20)N(4))(2)]·4H(2)O}(n), octa-hedrally coordinated Cd(II) ions, situated on crystallographic inversion centres, bearing trans-disposed chloride ligands, are linked into (4,4)-grid coordination polymer layers by tethering 1,4-bis-(3-pyridylmeth-yl)piperazine ligands. The layers are aligned parallel to the (01) crystal planes and aggregate by means of O-H⋯N, O-H⋯O and O-H⋯Cl hydrogen-bonding mechanisms imparted by cyclic water mol-ecule tetra-mers.