Iron(III) selenite

Iron(III) selenite
Identifiers

CAS Number	anhydrous: 15857-44-0^Y trihydrate: 41124-06-5^Y pentahydrate: 28184-72-7^Y heptahydrate: 31745-39-8^Y
3D model (JSmol)	anhydrous: Interactive image trihydrate: Interactive image
InChI InChI=1S/2Fe.3H2O3Se/c;;31-4(2)3/h;;3(H2,1,2,3)/q2*+3;;;/p-6 Key: KWCBONPMAFANBV-UHFFFAOYSA-H
SMILES anhydrous: [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-] trihydrate: [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-].O.O.O
Properties
Chemical formula	Fe₂(SeO₃)₃
Appearance	yellow crystals (trihydrate)^[1]
Density	3.537 g·cm⁻³ (trihydrate)^[2]
Structure
Crystal structure	R3c (No.161) (trihydrate)^[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Iron(III) selenite is an inorganic compound with the chemical formula Fe₂(SeO₃)₃. It exists anhydrous form and as various hydrates. The heptahydrate is produced by the reaction of ferric chloride and selenous acid (or sodium selenite) at a pH of 1.05.^[3] The pentahydrate has the structure of Fe₂(OH)₃(H₂O)₂(HSeO₃)₃.^[4] The single crystal diffraction of the trihydrate shows that its structure consists of two independent FeO₆ octahedrons and SeO₃²⁻ with a tetrahedral geometry.^[1]

The anhydrous salt decomposes into Fe₂O₃·2SeO₂ at 534 °C, generates 4Fe₂O₃·SeO₂ at 608 °C, and finally obtains Fe₂O₃ at 649 °C.^[5]

References

^ ^a ^b Aitor Larrañaga, José L. Mesa, José L. Pizarro, Luis Lezama, María I. Arriortua, Teófilo Rojo (May 2008). "Synthesis, thermal, spectroscopic and magnetic studies of the Mn(SeO3)·2H2O and Fe2(SeO3)3·3H2O selenites". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 69 (3): 1020–1026. doi:10.1016/j.saa.2007.06.019. PMID 17681850. Archived from the original on 2020-07-11. Retrieved 2020-12-26.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b Gerald Giester, Franz Pertlik (Aug 1994). "Synthesis and crystal structure of iron(III) selenate(IV) trihydrate, Fe2(SeO3)3 • 3H2O". Journal of Alloys and Compounds. 210 (1–2): 125–128. doi:10.1016/0925-8388(94)90126-0. Retrieved 2020-12-26.
^ Pinaev, G. F.; Volkova, V. P. Preparation and some properties of iron(III) selenite. Obshchaya i Prikladnaya Khimiya, 1970. 3: 33-39. ISSN: 0369-7045.
^ Maldagalieva, R. A.; Shokanov, A. K. Infrared spectroscopic study of the state of water molecules in crystal hydrates of transition metal selenites. Trudy Khimiko-Metallurgicheskogo Instituta, Akademiya Nauk Kazakhskoi SSR, 1973. 22: 16-20. ISSN: 0516-0324.
^ Bakeeva, S. S.; Muldagalieva, R. A.; Buketov, E. A.; Pashinkin, A. S. Thermal stability of neutral iron selenite. Trudy Khimiko-Metallurgicheskogo Instituta, Akademiya Nauk Kazakhskoi SSR, 1970. 15: 88-92. ISSN: 0516-0324.