title: catena-Poly[[[aqua-(5-nitro-benzene-1,2,3-tricarboxyl-ato-κO)copper(II)]-di-μ-aqua-[diaqua-sodium]-di-μ-aqua] tetra-hydrate].
abstract: In the heteronuclear coordination polymer, {[CuNa(C(9)H(2)NO(8))(H(2)O)(7)]·4H(2)O}(n), the Cu(II) atom is coordinated by six O atoms from five water mol-ecules and one 5-nitro-benzene-1,2,3-tricarboxyl-ate ligand in a slightly distorted octa-hedral geometry. The Na(+) cation is surrounded by six water mol-ecules in an irregular trigonal-prismatic geometry. The Cu and Na atoms are connected by water bridges, forming an infinite chain. O-H⋯O hydrogen bonds involving the coordinated and uncoordinated water mol-ecules connect the chains into a three-dimensional network.
authors.forename: Yong-Jie
authors.initials: YJ
authors.lastname: Ding
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: Zhao