Barium ferrate

Barium ferrate
Structural formula of barium(2+)	Wireframe model of aromatised ferrate
Names
	IUPAC name Barium ferrate(VI)
	Other names Barium ferrate(2-)
Identifiers
CAS Number	13773-23-4;
3D model (JSmol)	Interactive image;
ChemSpider	57448624;
	InChI InChI=1S/Ba.Fe.4O/q+2;;;;2*-1 Key: JFTTYFWNHKVEMY-UHFFFAOYSA-N;
	SMILES [Ba++].[O-][Fe]([O-])(=O)=O;
Properties
Chemical formula	BaFeO4
Molar mass	257,1646 g/mol
Appearance	Dark red, opaque crystals
Solubility in water	insoluble
Structure
Crystal structure	orthorhombic
Space group	Pnma, No. 62
	Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa). verify(what is?) Infobox references

Barium ferrateis thechemical compoundof formula BaFeO₄.This is a rare compound containingironin the +6oxidation state.^[2]The ferrate(VI) ion has two unpaired electrons, making itparamagnetic.^[3]It is isostructural withBaSO₄,and contains the tetrahedral[FeO₄]²⁻anion.^[4]

Structure

Theferrate(VI)anion is paramagnetic due to its twounpaired electronsand it has atetrahedral molecular geometry.^[3]

X-ray diffractionhas been used to determine the orthorhombic unit cell structure^[1](lattice vectors a ≠ b ≠ c, interaxial angles α=β=γ=90°)^[5]of nanocrystalline BaFeO₄.It crystallized in the Pnmaspace group(point group: D_2h) with lattice parametersa= 0.8880 nm,b= 0.5512 nm andc= 0.7214 nm.^[1]The accuracy of the X-Ray diffraction data has been verified by the lattice fringe intervals fromHigh-Resolution Transmission Electron Microscopy(HRTEM) and cell parameters calculated fromSelected Area Diffraction(SAED).^[1]

Characterization

Infraredabsorbance peaks of barium ferrate are observed at 870, 812, 780 cm⁻¹.^[7]

BaFeO₄follows theCurie–Weiss lawand has amagnetic momentof (2.92 ± 0.03) × 10⁻²³A m²(3.45 ± 0.1BM) with aWeiss constantof −89 K.^[9]

Preparation and chemistry

Barium ferrate(VI) can be prepared by both wet and dry synthetic methods. Dry synthesis is usually performed using a thermal technique,^[7]such as by heatingbarium hydroxideandiron(II) hydroxidein the presence ofoxygento about 800 to 900 °C.^[10]

Ba(OH)
₂+Fe(OH)
₂+O
₂→BaFeO
₄+ 2H
₂O

Wet methods employ both chemical and electrochemical techniques. For example, the ferrate anion forms when a suitable ironsaltis placed inalkaline conditionsand a strongoxidising agent,such assodium hypochlorite,is added.^[11]

2Fe(OH)
₃+ 3OCl⁻
+ 4OH⁻
→ 2FeO²⁻
₄+ 5H
₂O+ 3Cl⁻

Barium ferrate is then precipitated from solution by adding a solution of abarium(II)salt.^[11]Addition of a soluble barium salt to an alkali metal ferrate solution produces a maroon precipitate of barium ferrate, a crystal which has the same structure asbarium chromateand has approximately the same solubility.^[12]Barium ferrate has also been prepared by addingbarium oxideto a mixture sodium hypochlorite andferric nitrateat room temperature (or 0 °C).^[13]The purity of the product can be improved by carrying out the reaction at low temperature in the absence of carbon dioxide and by rapidly filtering and drying the precipitate, reducing the coprecipitation ofbarium hydroxideandbarium carbonateas impurities.^[12]

Uses

Barium ferrate is anoxidizing agentand is used as an oxidizing reagent in organic syntheses. Its other applications include removal of color, removal of cyanide, killing bacteria and contaminated and waste water treatment.^[7]

Salts of ferrate(VI) are energetic cathode materials in "super-iron" batteries. Cathodes containing ferrate(VI) compounds are referred to as "super-iron" cathodes due to their highly oxidized iron basis, multiple electron transfer, and high intrinsic energy. Among all ferrate(VI) salts, barium ferrate sustains unusually facile charge transfer, which is important for the high power domain ofalkaline batteries.^[8]

Reactions

Barium ferrate is the most stable of the ferrate(VI) compounds. It can be prepared in its purest state and has the most definite composition. Barium ferrate can be easily decomposed by all soluble acids, including carbonic acid. If carbon dioxide is passed through water on which hydrated barium ferrate is suspended, barium ferrate will decompose completely to formbarium carbonate,ferric hydroxide and oxygen gas. Alkaline sulfates decompose barium ferrate that has not been dried, forming barium sulfate, ferric hydroxide and oxygen gas.

References

^^a ^b ^c ^dNi, Xiao-Min; Ji, Ming-Rong; Yang, Zhi-Ping; Zheng, Hua-Gui (2004). "Preparation and structure characterization of nanocrystalline BaFeO₄".Journal of Crystal Growth.261(1): 82–86.Bibcode:2004JCrGr.261...82N.doi:10.1016/j.jcrysgro.2003.09.024.
^Briggs, J. G. R. (2005).Longman A-level course in chemistry(4th ed.).Pearson EducationSouth Asia. p. 536.ISBN 978-981-4105-08-8.
^^a ^bWiberg, Egon;Wiberg, Nils; Holleman, Arnold (2001).Inorganic chemistry.Academic Press.pp. 1457–1458.ISBN 978-0-12-352651-9.
^Wells, A.F. (1986).Structural inorganic chemistry(5th ed.). Oxford [Oxfordshire]:Clarendon Press.ISBN 978-0-19-855370-0.
^"IUCr".www.iucr.org.Retrieved2016-04-29.
^Ropp, Richard C. (2012).Encyclopedia of the Alkaline Earth Compounds.Newnes Press.ISBN 9780444595539.
^^a ^b ^cHenry-Chase, Adonica; Bhushan Tewari, Brij (2013)."Use to Ferrate (VI) A Green Chemical for the Environment Remediation"(PDF).Revista Boliviana de Química.30(1): 13–23.ISSN 0250-5460.
^^a ^bLicht, Stuart; Naschitz, Vera; Wang, Baohui (2002). "Rapid chemical synthesis of the barium ferrate super-iron Fe (VI) compound, BaFeO₄".Journal of Power Sources.109(1): 67–70.Bibcode:2002JPS...109...67L.doi:10.1016/s0378-7753(02)00041-1.
^Audette, R. J.; Quail, J. W. (1972). "Potassium, rubidium, cesium, and barium ferrates(VI). Preparations, infrared spectra, and magnetic susceptibilities".Inorganic Chemistry.11(8): 1904–1908.doi:10.1021/ic50114a034.
^Sharma, R. K. (2007)."Stabilisation of Fe (VI)".Textbook of Coordination Chemistry.New Delhi:Discovery Publishing House.p. 124.ISBN 9788183562232.
^^a ^bWulfsberg, Gary (1991)."pH and the stability of high oxidation states; Syntheses of oxo anions and their use as oxidizing agents".Principles of Descriptive Inorganic Chemistry.Sausalito, CA:University Science Books.pp. 142–143.ISBN 9780935702668.
^^a ^bGump, J. R.; Wagner, W. F.; Schreyer, J. M. (1954). "Preparation and analysis of barium ferrate(VI)".Analytical Chemistry.26(12): 1957.doi:10.1021/ac60096a027.ISSN 0003-2700.
^Herber, Rolfe H.; Johnson, David (1979). "Lattice dynamics and hyperfine interactions in M₂FeO₄(M = K⁺,Rb⁺,Cs⁺) and M'FeO4 (M' = Sr²⁺,Ba²⁺) ".Inorganic Chemistry.18(10): 2786–2790.doi:10.1021/ic50200a030.

[structure-1] Ni, Xiao-Min; Ji, Ming-Rong; Yang, Zhi-Ping; Zheng, Hua-Gui (2004). "Preparation and structure characterization of nanocrystalline BaFeO₄".Journal of Crystal Growth.261(1): 82–86.Bibcode:2004JCrGr.261...82N.doi:10.1016/j.jcrysgro.2003.09.024.

[2] Briggs, J. G. R. (2005).Longman A-level course in chemistry(4th ed.).Pearson EducationSouth Asia. p. 536.ISBN 978-981-4105-08-8.

[:0-3] Wiberg, Egon;Wiberg, Nils; Holleman, Arnold (2001).Inorganic chemistry.Academic Press.pp. 1457–1458.ISBN 978-0-12-352651-9.

[4] Wells, A.F. (1986).Structural inorganic chemistry(5th ed.). Oxford [Oxfordshire]:Clarendon Press.ISBN 978-0-19-855370-0.

[5] "IUCr".www.iucr.org.Retrieved2016-04-29.

[6] Ropp, Richard C. (2012).Encyclopedia of the Alkaline Earth Compounds.Newnes Press.ISBN 9780444595539.

[:2-7] Henry-Chase, Adonica; Bhushan Tewari, Brij (2013)."Use to Ferrate (VI) A Green Chemical for the Environment Remediation"(PDF).Revista Boliviana de Química.30(1): 13–23.ISSN 0250-5460.

[:3-8] Licht, Stuart; Naschitz, Vera; Wang, Baohui (2002). "Rapid chemical synthesis of the barium ferrate super-iron Fe (VI) compound, BaFeO₄".Journal of Power Sources.109(1): 67–70.Bibcode:2002JPS...109...67L.doi:10.1016/s0378-7753(02)00041-1.

[9] Audette, R. J.; Quail, J. W. (1972). "Potassium, rubidium, cesium, and barium ferrates(VI). Preparations, infrared spectra, and magnetic susceptibilities".Inorganic Chemistry.11(8): 1904–1908.doi:10.1021/ic50114a034.

[10] Sharma, R. K. (2007)."Stabilisation of Fe (VI)".Textbook of Coordination Chemistry.New Delhi:Discovery Publishing House.p. 124.ISBN 9788183562232.

[Wulfsberg-11] Wulfsberg, Gary (1991)."pH and the stability of high oxidation states; Syntheses of oxo anions and their use as oxidizing agents".Principles of Descriptive Inorganic Chemistry.Sausalito, CA:University Science Books.pp. 142–143.ISBN 9780935702668.

[Gump-12] Gump, J. R.; Wagner, W. F.; Schreyer, J. M. (1954). "Preparation and analysis of barium ferrate(VI)".Analytical Chemistry.26(12): 1957.doi:10.1021/ac60096a027.ISSN 0003-2700.

[13] Herber, Rolfe H.; Johnson, David (1979). "Lattice dynamics and hyperfine interactions in M₂FeO₄(M = K⁺,Rb⁺,Cs⁺) and M'FeO4 (M' = Sr²⁺,Ba²⁺) ".Inorganic Chemistry.18(10): 2786–2790.doi:10.1021/ic50200a030.

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