Iron(III) perchlorate

Chemical compound From Wikipedia, the free encyclopedia

Iron(III) perchlorate, also known as ferric perchlorate, is an inorganic chemical compound with the formula Fe(ClO4)3·nH2O, where n can range from 0 to 9. The most common form is the nonahydrate, Fe(ClO4)3·9H2O, which is a hygroscopic pale violet crystalline solid, but samples are often partially hydrolyzed and/or contaminated with iron(III) chloride, giving them a yellow color.[5]

Quick facts Names, Identifiers ...
Iron(III) perchlorate
Names
Other names
  • Ferric perchlorate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.538 Edit this at Wikidata
EC Number
  • 236-908-0
  • InChI=1S/3ClHO4.Fe/c3*2-1(3,4)5;/h3*(H,2,3,4,5);/q;;;+3/p-3
  • hydrate: InChI=1S/3ClHO4.Fe.H2O/c3*2-1(3,4)5;;/h3*(H,2,3,4,5);;1H2/q;;;+3;/p-3
    Key: PFPIMAZLJXJVAN-UHFFFAOYSA-K
  • hexahydrate: InChI=1S/3ClHO4.Fe.6H2O/c3*2-1(3,4)5;;;;;;;/h3*(H,2,3,4,5);;6*1H2/q;;;+3;;;;;;/p-3
    Key: GJMIMISVJLOUGG-UHFFFAOYSA-K
  • nonahydrate: InChI=1S/3ClHO4.Fe.9H2O/c3*2-1(3,4)5;;;;;;;;;;/h3*(H,2,3,4,5);;9*1H2/q;;;+3;;;;;;;;;/p-3
    Key: JWCPSNBNEQGKFX-UHFFFAOYSA-K
  • [O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+3]
  • hydrate: O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+3]
  • hexahydrate: O.O.O.O.O.O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+3]
  • nonahydrate: O.O.O.O.O.O.O.O.O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+3]
Properties
Fe(ClO4)3
Molar mass 354.19 g/mol (anhydrous)
516.34 g/mol (nonahydrate)
Appearance Canary yellow solid (anhydrous)[1]
Pale violet solid (nonahydrate)[2]
Density 2.03 g/cm3 (nonahydrate)[3]
Melting point 110 °C (230 °F; 383 K)[2] (decomposition, nonahydrate)
nonahydrate
74.32 g/100 mL (0 °C)
79.86 g/100 mL (25 °C)[4]
Structure[3]
Trigonal
R3c
a = 16.19 Å, c = 11.24 Å
2553 Å3
octahedral (around Fe)
Hazards
GHS labelling:
GHS03: OxidizingGHS07: Exclamation mark
Danger
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
2
0
1
OX
Related compounds
Other anions
 Iron(III) nitrate
Other cations
 Manganese(II) perchlorate
Cobalt(II) perchlorate
Related compounds
 Iron(II) perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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History

Iron(III) perchlorate was first observed by Georges-Simon Serullas in 1831 as an oxidation product of iron(II) perchlorate, who was attempting to produce various metal perchlorates after Friedrich von Stadion discovered the perchlorate ion. However, it was not properly characterized until 1935 by Folke Lindstrand [sv].[6][7][2]

Preparation

The nonahydrate is produced by refluxing a mixture of iron(III) oxide-hydroxide and aqueous 70% perchloric acid:[2]

FeO(OH) + 3 HClO4 → Fe(ClO4)3 + 2 H2O

It can also be prepared by the reaction of iron(III) chloride and aqueous perchloric acid, followed by repeated recrystallization in perchloric acid.[5][8]

In comparison, the synthesis of the anhydrous form is much more difficult. It is produced by the reaction of iron(III) chloride and dichlorine hexoxide at 20 °C:[1][9]

2 FeCl3 + 7 Cl2O6 → ClO2​Fe2​(ClO4​)7 + 6 ClO2 + 3 Cl2​

The resulting ClO2​Fe2​(ClO4​)7 is heated under a vacuum at 60 °C to yield the canary yellow anhydrous iron(III) perchlorate.[1]

Hydrates other than the nonahydrate, such as the hexahydrate, from the dehydration of the nonahydrate in the presence of sulfuric acid, and the dihydrate, from the reaction of anhydrous perchloric acid and iron(III) chloride, have been reported.[9][10]

Structure

The nonahydrate, structurally formulated [Fe(H2O)6](ClO4)3·3H2O, has a trigonal crystal structure and consists of discrete octahederal [Fe(H2O)6]3+ centers as well as perchlorate and three molecules of water of crystallization.[3][8]

The anhydrous form, which has been probed by IR spectroscopy, consists of bidentate perchlorate ligands.[1]

Reactions and applications

Iron(III) perchlorate dissolves in water to form [Fe(H2O)6]3+ and ClO4– ions. The [Fe(H2O)6]3+ partially hydrolyses:[11][12]

[Fe(H2O)6]3+ ⇌ [Fe(H2O)5OH]2+ + H+

Dilute solutions of iron(III) perchlorate slowly precipitate iron(III) hydroxide particles, whereas concentrated solutions do not, because the higher acidity prevents hydroxide formation. Hydrolysis can also be suppressed by adding perchloric acid. The above behavior parallels that of iron(III) nitrate solutions.[11][12]

The nonahydrate decomposes at around 110 °C to an unknown basic perchlorate. The anhydrous form, when heated, similarly decomposes to an unknown basic perchlorate.[2][1]

Iron(III) perchlorate has very limited applications in organic synthesis. The anhydrous and dihydrate have been studied as a cationic polymerization initiator for alkenes. The nonahydrate has been studied for use as a catalyst in various organic reactions, including multicomponent condensation reactions.[10][13][14][15]

References

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