Iron(III) fluoride

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Iron(III) fluoride
Aluminium-trifluoride-3D-polyhedra.png
FeF3structure.jpg
Names
Other names
iron trifluoride, ferric fluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.093 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • NO6865000
UNII
  • InChI=1S/3FH.Fe/h3*1H;/q;;;+3/p-3 Yes check.svgY
    Key: SHXXPRJOPFJRHA-UHFFFAOYSA-K Yes check.svgY
  • InChI=1/3FH.Fe/h3*1H;/q;;;+3/p-3
    Key: SHXXPRJOPFJRHA-DFZHHIFOAS
  • F[Fe](F)F
Properties
FeF3
Molar mass 112.840 g/mol (anhydrous)
166.89 g/mol (trihydrate)
Appearancepale green crystals
Density 3.87 g/cm3 (anhydrous)
2.3 g/cm3 (trihydrate)
Melting point >1,000 °C (1,830 °F; 1,270 K)
slightly soluble (anhydrous)
49.5 g/100 mL (trihydrate)
Solubility negligible in alcohol, ether, benzene
+13,760·10−6 cm3/mol
Structure
Rhombohedral, hR24
R-3c, No. 167
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg [1]
Danger [1]
H302, H312, H314, H332 [1]
P260, P301+P330+P331, P303+P361+P353, P305+P351+P338, P405, P501 [1]
Safety data sheet (SDS) External SDS
Related compounds
Other anions
Iron(III) oxide, Iron(III) chloride
Other cations
Manganese(III) fluoride, Cobalt(III) fluoride, Ruthenium(III) fluoride
Related compounds
 Iron(II) fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Iron(III) fluoride, also known as ferric fluoride, are inorganic compounds with the formula FeF3(H2O)x where x = 0 or 3. They are mainly of interest by researchers, unlike the related iron(III) chlorides. Anhydrous iron(III) fluoride is white, whereas the hydrated forms are light pink. [2]

Contents

Chemical and physical properties

Iron(III) fluoride is a thermally robust, antiferromagnetic [3] solid consisting of high spin Fe(III) centers, which is consistent with the pale colors of all forms of this material. Both anhydrous iron(III) fluoride as well as its hydrates are hygroscopic.

Structure

The anhydrous form adopts a simple structure with octahedral Fe(III)F6 centres interconnected by linear Fe-F-Fe linkages. In the language of crystallography, the crystals are classified as rhombohedral with an R-3c space group. [4] The structural motif is similar to that seen in ReO3. Although the solid is nonvolatile, it evaporates at high temperatures, the gas at 987  °C consists of FeF3, a planar molecule of D3h symmetry with three equal Fe-F bonds, each of length 176.3 pm. [5] At very high temperatures, it decomposes to give FeF2 and F2. [4]

Two crystalline forms—or more technically, polymorphs—of FeF3·3H2O are known, the α and β forms. These are prepared by evaporation of an HF solution containing Fe3+ at room temperature (α form) and above 50 °C (β form). The space group of the β form is P4/m, and the α form maintains a P4/m space group with a J6 substructure. The solid α form is unstable and converts to the β form within days. The two forms are distinguished by their difference in quadrupole splitting from their Mössbauer spectra. [6]

Preparation, occurrence, reactions

Anhydrous iron(III) fluoride is prepared by treating virtually any anhydrous iron compound with fluorine. More practically and like most metal fluorides, it is prepared by treating the corresponding chloride with hydrogen fluoride: [7]

FeCl3 + 3 HF → FeF3 + 3 HCl

It also forms as a passivating film upon contact between iron (and steel) and hydrogen fluoride. [8] The hydrates crystallize from aqueous hydrofluoric acid. [6]

The material is a fluoride acceptor. With xenon hexafluoride it forms [FeF4][XeF5]. [4]

Pure FeF3 is not yet known among minerals. However, hydrated form is known as the very rare fumarolic mineral topsøeite. Generally a trihydrate, its chemistry is slightly more complex: FeF[F0.5(H2O)0.5]4·H2O. [9] [10]

Applications

The primary commercial use of iron(III) fluoride in the production of ceramics. [11]

Some cross coupling reaction are catalyzed by ferric fluoride-based compounds. Specifically the coupling of biaryl compounds are catalyzed by hydrated iron(II) fluoride complexes of N-heterocyclic carbene ligands. Other metal fluorides also catalyse similar reactions. [12] [13] Iron(III) fluoride has also been shown to catalyze chemoselective addition of cyanide to aldehydes to give the cyanohydrins. [14]

Safety

The anhydrous material is a powerful dehydrating agent. The formation of ferric fluoride may have been responsible for the explosion of a cylinder of hydrogen fluoride gas. [15]

Related Research Articles

<span class="mw-page-title-main">Iron(III) oxide</span> Chemical compound

Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron for the steel industry. Fe2O3 is readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as Hydrous ferric oxide.

<span class="mw-page-title-main">Iron oxide</span> Class of chemical compounds composed of iron and oxygen

Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are nonstoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of which is rust.

<span class="mw-page-title-main">Iron(III) chloride</span> Inorganic compound

Iron(III) chloride is the inorganic compound with the formula FeCl3. Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The color depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red.

<span class="mw-page-title-main">Cerium(III) chloride</span> Chemical compound

Cerium(III) chloride (CeCl3), also known as cerous chloride or cerium trichloride, is a compound of cerium and chlorine. It is a white hygroscopic salt; it rapidly absorbs water on exposure to moist air to form a hydrate, which appears to be of variable composition, though the heptahydrate CeCl3·7H2O is known. It is highly soluble in water, and (when anhydrous) it is soluble in ethanol and acetone.

<span class="mw-page-title-main">Iron(II) chloride</span> Chemical compound

Iron(II) chloride, also known as ferrous chloride, is the chemical compound of formula FeCl2. It is a paramagnetic solid with a high melting point. The compound is white, but typical samples are often off-white. FeCl2 crystallizes from water as the greenish tetrahydrate, which is the form that is most commonly encountered in commerce and the laboratory. There is also a dihydrate. The compound is highly soluble in water, giving pale green solutions.

<span class="mw-page-title-main">Manganese(III) fluoride</span> Chemical compound

Manganese(III) fluoride (also known as Manganese trifluoride) is the inorganic compound with the formula MnF3. This red/purplish solid is useful for converting hydrocarbons into fluorocarbons, i.e., it is a fluorination agent. It forms a hydrate and many derivatives.

Phosphorus trifluoride (formula PF3), is a colorless and odorless gas. It is highly toxic and reacts slowly with water. Its main use is as a ligand in metal complexes. As a ligand, it parallels carbon monoxide in metal carbonyls, and indeed its toxicity is due to its binding with the iron in blood hemoglobin in a similar way to carbon monoxide.

<span class="mw-page-title-main">Iridium(III) chloride</span> Chemical compound

Iridium(III) chloride is the inorganic compound with the formula IrCl3. The anhydrous compound is relatively rare, but the related hydrate is useful for preparing other iridium compounds. The anhydrous salt is a dark green crystalline solid. More commonly encountered is the trihydrate IrCl3(H2O)3.

<span class="mw-page-title-main">Iron(III) phosphate</span> Chemical compound

Iron(III) phosphate, also ferric phosphate, is the inorganic compound with the formula FePO4. Several related materials are known, including four polymorphs of FePO4 and two polymorphs of the dihydrate FePO4·(H2O)2. These materials find few technical applications as well as occurring in the mineral kingdom.

<span class="mw-page-title-main">Chromium(III) fluoride</span> Chemical compound

Chromium(III) fluoride is the name for the inorganic compounds with the chemical formula CrF3 as well as several related hydrates. The compound CrF3 is a green crystalline solid that is insoluble in common solvents, but the coloured hydrates [Cr(H2O)6]F3 and [Cr(H2O)6]F3•3H2O are soluble in water. The trihydrate is green, and the hexahydrate is violet. The anhydrous form sublimes at 1100–1200 °C.

<span class="mw-page-title-main">Cobalt(III) fluoride</span> Chemical compound

Cobalt(III) fluoride is the inorganic compound with the formula CoF3. Hydrates are also known. The anhydrous compound is a hygroscopic brown solid. It is used to synthesize organofluorine compounds.

<span class="mw-page-title-main">Iron(II) fluoride</span> Chemical compound

Iron(II) fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF2. It forms a tetrahydrate FeF2·4H2O that is often referred to by the same names. The anhydrous and hydrated forms are white crystalline solids.

<span class="mw-page-title-main">Cobalt(II) fluoride</span> Chemical compound

Cobalt(II) fluoride is a chemical compound with the formula (CoF2). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (TN=37.7 K) The formula is given for both the red tetragonal crystal, (CoF2), and the tetrahydrate red orthogonal crystal, (CoF2·4H2O). CoF2 is used in oxygen-sensitive fields, namely metal production. In low concentrations, it has public health uses. CoF2 is sparingly soluble in water. The compound can be dissolved in warm mineral acid, and will decompose in boiling water. Yet the hydrate is water-soluble, especially the di-hydrate CoF2·2H2 O and tri-hydrate CoF2·3H2O forms of the compound. The hydrate will also decompose with heat.

<span class="mw-page-title-main">Iron(III) oxide-hydroxide</span> Chemical compound

Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH).

<span class="mw-page-title-main">Zinc fluoride</span> Chemical compound

Zinc fluoride (ZnF2) is an inorganic chemical compound. It is encountered as the anhydrous form and also as the tetrahydrate, ZnF2 · 4H2O (rhombohedral crystal structure). It has a high melting point and has the rutile structure containing 6 coordinate zinc, which suggests appreciable ionic character in its chemical bonding. Unlike the other zinc halides, ZnCl2, ZnBr2 and ZnI2, it is not very soluble in water.

Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X− couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.

<span class="mw-page-title-main">Bismuth trifluoride</span> Chemical compound

Bismuth(III) fluoride or bismuth trifluoride is a chemical compound of bismuth and fluorine. The chemical formula is BiF3. It is a grey-white powder melting at 649 °C.

<span class="mw-page-title-main">Cobalt(II) iodide</span> Chemical compound

Cobalt(II) iodide or cobaltous iodide are the inorganic compounds with the formula CoI2 and the hexahydrate CoI2(H2O)6. These salts are the principal iodides of cobalt.

The Mukaiyama hydration is an organic reaction involving formal addition of an equivalent of water across an olefin by the action of catalytic bis(acetylacetonato)cobalt(II) complex, phenylsilane and atmospheric oxygen to produce an alcohol with Markovnikov selectivity.

<span class="mw-page-title-main">Curium(III) fluoride</span> Chemical compound

Curium(III) fluoride or curium trifluoride is the chemical compound composed of curium and fluorine with the formula CmF3. It is a white, nearly insoluble salt that has the same crystal structure as LaF3. It precipitates as a hydrate when fluoride ions are added to a weakly acidic Cm(III) solution; alternatively it can be synthesized by reacting hydrofluoric acid with Cm(OH)3. The anhydrous form is then obtained by desiccation or by treatment with hydrogen fluoride gas.

References

  1. 1 2 3 4 "Iron(III) Fluoride". American Elements . Retrieved November 5, 2018.
  2. ↑ Housecroft, Catherine E.; Sharpe, Alan G. (2008) Inorganic Chemistry (3rd ed.), Pearson: Prentice Hall. ISBN   978-0-13-175553-6.
  3. ↑ Wollan, E. O.; Child, H. R.; Koehler, W. C.; Wilkinson. M. K. (November 1958). "Antiferromagnetic properties of the iron group trifluorides". Physical Review. 112 (4): 1132–1136. Bibcode:1958PhRv..112.1132W. doi:10.1103/PhysRev.112.1132.
  4. 1 2 3 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  5. ↑ Hargittai, M.; Kolonits, M.; Tremmel, J.; Fourquet. J.; Ferey, G. (January 1990). "The molecular geometry of iron trifluoride from electron diffraction and a reinvestigation of aluminum trifluoride". Structural Chemistry. 1 (1): 75–78. doi:10.1007/BF00675786. S2CID   96178006.
  6. 1 2 Karraker, D. G.; Smith, P. K. (March 1992). "α- and β-FeF3•3H2O Revisited: Crystal Structure and 57Fe Mössbauer Spectra". Inorganic Chemistry. 31 (6): 1118–1120. doi:10.1021/ic00032a042.
  7. ↑ Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 266-7.
  8. ↑ J. Aigueperse, P. Mollard, D. Devilliers, M. Chemla, R. Faron, R. Romano, J. P. Cuer, "Fluorine Compounds, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi : 10.1002/14356007.a11_307
  9. ↑ "Topsøeite".
  10. ↑ "List of Minerals". 21 March 2011.
  11. ↑ "Ferric Fluoride." CAMEO Chemicals. National Oceanic and Atmospheric Administration. Web. 7 Apr. 2010. <http://cameochemicals.noaa.gov/chemical/3468>
  12. ↑ Hatakeyama, T.; Nakamura M. (July 2007). "Iron-Catalyzed Selective Biaryl Coupling: Remarkable Suppression of Homocoupling by the Fluoride Anion". Journal of the American Chemical Society. 129 (32): 9844–9845. doi:10.1021/ja073084l. PMID   17658810.
  13. ↑ Hatakeyama, T.; Hashimoto, S.; Ishizuka, K.; Nakamura, M. (July 2009). "Highly Selective Biaryl Cross-Coupling Reactions between Aryl Halides and Aryl Grignard Reagents: A New Catalyst Combination of N-Heterocyclic Carbenes and Iron, Cobalt, and Nickel Fluorides". Journal of the American Chemical Society. 131 (33): 9844–9845. doi:10.1021/ja9039289. PMID   19639999.
  14. ↑ Bandgar, B. T.; Kamble, V. T. (July 2001). "Organic Reactions in aqueous medium: FeF3 catalyzed chemoselective addition of cyanotrimethylsilane to aldehydes". Green Chemistry. 3 (5): 265. doi:10.1039/b106872p.
  15. ↑ "A recent explosion of a lecture-size cylinder of hydrogen fluoride ... has renewed concerns that compressed gas cylinders can be especially dangerous" (PDF). University of California San Francisco. Archived from the original (PDF) on 2006-09-01.
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