Disodium rhodizonate: a powder diffraction study

The crystal structure of the title compound, disodium 1,2,3,4-tetra­oxo-5-cyclo­hexene-5,6-diolate, 2Na⁺·C₆O₆^2-, is built up of alternating layers of hexa­gonally packed Na⁺ cations and rhodizonate dianions. The rhodizon­ate dianion has a slightly twisted conformation.