Poly[[hexa-μ-aqua-diaqua­bis­(μ(4)-dihydrogen benzene-1,2,4,5-tetra­carboxyl­ato)magnesiumdisodium] dihydrate]

The asymmetric unit of the title compound, {[MgNa(2)(C(10)H(4)O(8))(2)(H(2)O)(8)]·2H(2)O}(n), contains one octa­hedrally coordin­ated Mg(II) atom (site symmetry 2/m), one octahedrally coordinated Na(I) atom (site symmetry 2) and one half of the dihydrogen benzene-1,2,4,5-tetra­carboxyl­ate (btec) ligand, the second half of the ligand being generated by a twofold rotation axis. The basic framework of the title compound features infinite (–Na–Na–Mg–)(n) chains along [10-1] with the metal cations bridged by the coordinating water molecules. The chains are isolated from each other by μ(4)-bridging btec ligands, which form inter­molecular O—H⋯O hydrogen bonds to uncoordinated water mol­ecules and the coordinated water mol­ecules of a neighbouring chain. In each btec ligand, there are also intramolecular O—H⋯O hydrogen bonds.