Crystal data for sodium heptahydrogenselenite, NaH7(SeO3)4

NaH7(SeO3)4 crystallized under the conditions derived from the solubility diagram of the Na2SeO3–H2SeO3–H2O system at 298 K. The Weissenberg patterns showed systematic absences indicating the space group P21/c. The cell dimensions were refined by least squares from powder diffractometer data. a = 5.784(2), b = 4.938(2), c = 20.08(1) A, β = 100.39 (3)°, V = 564.1(4) A3, Z = 2, Dm = 3.173(3), Dx = 3.166 Mg m−3. Cu Kα radiation. The crystal structure is unknown. The JCPDS Diffraction File No. for NaH7(SeO3)4 is 34-1488.