Ferric oxalate

Chemical compound From Wikipedia, the free encyclopedia

Ferric oxalate, also known as iron(III) oxalate, refers to inorganic compounds with the formula Fe2(C2O4)3(H2O)x but could also refer to salts of [Fe(C2O4)3]3-. Fe2(C2O4)3(H2O)x are coordination polymers with varying degrees of hydration. The coordination complex with the formula [Fe(C2O4)3]3- forms a variety of salts, a well-known example being potassium ferrioxalate. This article emphasizes the coordination polymers.

Quick facts Names, Identifiers ...
Ferric oxalate
Names
Systematic IUPAC name
iron(3+) ethanedioate (2:3)
Other names
Iron(III) oxalate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.019.047 Edit this at Wikidata
EC Number
  • 220-951-7
UNII
  • InChI=1S/3C2H2O4.2Fe/c3*3-1(4)2(5)6;;/h3*(H,3,4)(H,5,6);;/q;;;2*+3/p-6
  • [Fe+3].[Fe+3].O=C([O-])C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O
Properties
C6Fe2O12
Molar mass 375.747 g/mol
Appearance Pale yellow solid (anhydrous)
Lime green solid (hexahydrate)
Odor odorless
Melting point 365.1 °C (689.2 °F)
slightly soluble
Hazards
GHS labelling:[1]
GHS07: Exclamation mark
Warning
H302+H312
P264, P270, P280, P301+P317, P302+P352, P317, P321, P330, P362+P364, P501
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Close

Structure

Tetrahydrate

Structure of hydrated ferric oxalate Color code: red=O, white = H, blue = Fe, gray = C.
Room temperature Mössbauer spectrum of Fe2(C2O4)3·4H2O[2]

According to X-ray crystallography of the tetrahydrate Fe2(C2O4)3 · 4 H2O, iron is octahedrally coordinated. The oxalate ligands are bridging: some through all four oxygen atoms, some with two oxygen atoms. Half of the water is lattice water, being situated between chains of Fe oxalates.

The Mössbauer spectrum of Fe2(C2O4)3 · 4 H2O exhibits a doublet with an isomer shift of 0.38 mm/s, and a quadrupole splitting of 0.40 mm/s, suggesting a high spin Fe3+ in distorted octahedral coordination.[2][3]

Production

Ferric oxalate may be produced by reaction of iron(III) hydroxide and solution of oxalic acid:

2Fe(OH)3 + 3H2C2O4 → Fe2(C2O4)3 + 6H2O

Uses

Dentistry

Like many oxalates, ferric oxalate has been investigated as a short-term treatment for dentin hypersensitivity.[4] It is used in certain toothpaste formulations; however, its effectiveness has been questioned.[5]

Photography

Ferric oxalate is used as the light-sensitive element in the Kallitype photographic printing process; and the platinotype process Platinum/Palladium Printing.

Batteries

Ferric oxalate tetrahydrate has been investigated as a possible cheap material for the positive electrode (cathode) for lithium-ion batteries. It can intercalate lithium ions at an average potential of 3.35 V, and has shown a sustainable capacity of 98 mAh/g.[2] Additionally, ferric oxalate is one synthetic precursor to lithium iron phosphate, a popular Li-ion battery cathode.

Organic synthesis

Ferric oxalate hexahydrate is used with sodium borohydride for radical Markovnikov hydrofunctionalization reactions of alkenes.[6]

References

Related Articles

Wikiwand AI