Poly[diaqua-μ(3)-4-nitro-phthalato-copper(II)].

In the title complex, [Cu(C(8)H(3)NO(6))(H(2)O)(2)](n), the two carboxyl-ate groups of the 4-nitro-phthalate dianion ligands have monodentate and 1,3-bridging bonding modes, respectively. The Cu atom shows an approximate square-pyramidal coordination as it is bonded to O atoms from the carboxyl-ate groups of three 4-nitro-phthalate ligands and two O atoms of the non-equivalent coordinated water mol-ecules. Other Cu atoms in the coordination polymer are connected into a two-dimensional layer in the ab plane. The layers are aggregated to a three-dimensional structure through inter-layer hydrogen bonding involving an O atom of a nitro group. The whole three-dimensional structure is further maintained and stabilized by intra-layer hydrogen bonds between the O atoms of the carboxyl-ate groups and the coordinated water mol-ecules.