Dihydro­nium tetra­chromate(VI), (H₃O)₂Cr₄O₁₃

The crystal structure of (H₃O)₂Cr₄O₁₃ is isotypic with K₂Cr₄O₁₃. The finite tetra­chromate anion in the title structure consists of four vertex-sharing CrO₄ tetra­hedra and exhibits a typical zigzag arrangement. The crystal packing is stabilized by hydrogen bonds between these anions and hydro­nium cations. The two different hydro­nium cations are surrounded by nine O atoms of tetra­chromate anions, with O...O distances ranging between 2.866 (8) and 3.282 (7) Å.