Iron(III) selenite

{{Chembox

| Name =

| ImageFile = Iron(III)_selenite_heptahydrate.ვკ.jpg

| ImageName = Iron(III) selenite heptahydrate

| IUPACName =

| OtherNames =

| Section1 = {{Chembox Identifiers

| CASNo = 15857-44-0

| CASNo_Ref = {{cascite|correct|CAS}}

| index_label = anhydrous

| CASNo1 = 41124-06-5

| CASNo1_Ref = {{cascite|correct|CAS}}

| index1_label = trihydrate

| CASNo2 = 28184-72-7

| CASNo2_Ref = {{cascite|correct|CAS}}

| index2_label = pentahydrate

| CASNo3 = 31745-39-8

| CASNo3_Ref = {{cascite|correct|CAS}}

| index3_label = heptahydrate

| ChemSpiderID = 13950567

| PubChem = 15804695

| SMILES = [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-]

| SMILES1 = [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-].O.O.O

| SMILES2 = [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-].O.O.O.O.O

| SMILES3 = [Fe+3].[Fe+3].[O-][Se](=O)[O-].[O-][Se](=O)[O-].[O-][Se](=O)[O-].O.O.O.O.O.O.O

| StdInChI=1S/2Fe.3H2O3Se/c;;3*1-4(2)3/h;;3*(H2,1,2,3)/q2*+3;;;/p-6

| StdInChIKey=KWCBONPMAFANBV-UHFFFAOYSA-H

}}

| Section2 = {{Chembox Properties

| Formula = Fe₂(SeO₃)₃

| MolarMass =

| Appearance = yellow crystals (trihydrate){{cite journal|journal=Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy|volume=69|issue=3|language=en|date=May 2008|pages=1020–1026|doi=10.1016/j.saa.2007.06.019|url=https://linkinghub.elsevier.com/retrieve/pii/S138614250700323X|title=Synthesis, thermal, spectroscopic and magnetic studies of the Mn(SeO3)·2H2O and Fe2(SeO3)3·3H2O selenites|accessdate=2020-12-26|author=Aitor Larrañaga, José L. Mesa, José L. Pizarro, Luis Lezama, María I. Arriortua, Teófilo Rojo|pmid=17681850 |archive-date=2020-07-11|archive-url=https://web.archive.org/web/20200711014925/https://linkinghub.elsevier.com/retrieve/pii/S138614250700323X|url-status=dead}}

| Density = 3.537 g·cm⁻³ (trihydrate){{cite journal|journal=Journal of Alloys and Compounds|volume=210|issue=1–2|language=en|date=Aug 1994|pages=125–128|doi=10.1016/0925-8388(94)90126-0|url=https://linkinghub.elsevier.com/retrieve/pii/0925838894901260|title=Synthesis and crystal structure of iron(III) selenate(IV) trihydrate, Fe2(SeO3)3 • 3H2O|accessdate=2020-12-26|author=Gerald Giester, Franz Pertlik}}

| MeltingPt =

| BoilingPt =

| Solubility = }}

| Section3 = {{Chembox Structure

| Coordination =

| CrystalStruct = R3c (No.161) (trihydrate)

| MolShape = }}

| Section4 = {{Chembox Hazards

| MainHazards =

| FlashPt =

| Autoignition = }}

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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.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. The pentahydrate has the structure of Fe₂(OH)₃(H₂O)₂(HSeO₃)₃.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. The single crystal diffraction of the trihydrate shows that its structure consists of two independent FeO₆ octahedrons and SeO₃²⁻ with a tetrahedral geometry.

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