Iron(II) selenate explained

Iron(II) selenate (ferrous selenate) is an inorganic compound with the formula FeSeO4. It has anhydrous and several hydrate forms. The pentahydrate has the structure, [Fe(H<sub>2</sub>O)<sub>4</sub>]SeO4•H2O, isomorphous to the corresponding iron(II) sulfate.[1] Heptahydrate is also known, in form of unstable green crystalline solid.

Preparation

Iron(II) selenate can be prepared by the reaction of saturated sodium selenate and iron(II) sulfate at 80 °C. When cooled to room temperature, crystalline iron(II) selenate precipitates from the solution.[2]

Na2SeO4 (sat.) + FeSO4 → Na2SO4 + FeSeO4The reaction of iron and selenic acid produces iron(II) selenate as well, but with a side product:[3]

Fe + H2SeO4 → FeSeO4 + H2

3 Fe + 4 H2SeO4 → 3 FeSeO4 + Se + 4 H2O

Other species containing oxoanion of selenium

Double salts like the Tutton's salts (NH4)2Fe(SeO4)2•6H2O and K2Fe(SeO4)2•6H2O are known.

In addition to the ferrous (Fe2+) salt, the ferric (Fe3+) salt iron(III) selenate, Fe2(SeO4)3, has also been reported.[4]

However, iron(II) selenite (FeSeO3) is unknown, though the selenite and pyroselenite of iron(III) was published.[5]

Notes and References

  1. K. Heinzinger, G. Pálinkás, Hubertus Kleeberg. Interactions of Water in Ionic and Nonionic Hydrates: Proceedings of a Symposium in honour of the 65th birthday of W.A.P. Luck Marburg/FRG, 2.–3.4. 1987. Springer-Verlag Berlin Heidelberg, 1987
  2. Filonenko, E. N.; Vergeichik, E. N.. Preparation and analysis of cobalt (II) selenate and iron (II) selenate. Farmatsiya (Moscow), 1998. 47 (3): 36-37
  3. A E H Tutton. Selenic Acid and Iron. - Reduction of Selenic Acid by Nascent Hydrogen and Hydrogen Sulphide. - Preparation of Ferrous Selenate and Double Selenates of Iron Group. Proceedings of the Royal Society A, 1918, 94 (241) :352-361
  4. G Giester, F Pertlik. Synthesis and crystal structure of iron(III) selenate(IV) trihydrate, Fe2(SeO3)3·3H2O. Journal of Alloys & Compounds, 1994, 210 (1-2) :125-128
  5. Pinaev, G. F.; Stukan, R. A.; Makarov, E. F.. Moessbauer effect in iron(3+) selenites. Zhurnal Neorganicheskoi Khimii, 1977. 22 (7): 1731-1733