Poly[penta-μ-aqua-μ(6)-methyl-ene-disulfonato-μ(5)-methyl-enedisulfonato-tetra-sodium(I)].

The title compound, [Na(4)(CH(2)O(6)S(2))(2)(H(2)O)(5)](n), was crystallized from an aqueous solution. The sodium ions are surrounded and bridged by O atoms from coordinated water mol-ecules and sulfonate ions in a three-dimensional neutral network. The crystal structure is also stabilized by an intricate system of hydrogen bonds.