Iron(II) oxalate

Last updated
Iron(II) oxalate
Iron(II)-oxalate-sample.jpg
Fe(C2O4)-2D-ionic.png
Names
IUPAC name
Iron(II) oxalate
Other names
Iron oxalate
Ferrous oxalate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.007.472 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • (anhydrous):208-217-4
  • (dihydrate):611-981-5
PubChem CID
UNII
  • InChI=1S/3C2H2O4.2Fe/c3*3-1(4)2(5)6;;/h3*(H,3,4)(H,5,6);;/q;;;2*+3/p-6 X mark.svgN
    Key: VEPSWGHMGZQCIN-UHFFFAOYSA-H X mark.svgN
  • (dihydrate):InChI=1S/C2H2O4.Fe.2H2O/c3-1(4)2(5)6;;;/h(H,3,4)(H,5,6);;2*1H2/q;+2;;/p-2
    Key: NPLZZSLZTJVZSX-UHFFFAOYSA-L
  • (anhydrous):[Fe+2].O=C([O-])-C([O-])=O
  • (dihydrate):C(=O)(C(=O)[O-])[O-].O.O.[Fe+2]
Properties
FeC2O4 (anhydrous)
FeC2O4 · 2 H2O (dihydrate)
Molar mass 143.86 g/mol (anhydrous)
179.89 g/mol (dihydrate)
Appearanceyellow powder
Odor odorless
Density 2.28 g/cm3
Melting point dihydrate: 150–160 °C (302–320 °F; 423–433 K)
(decomposes)
dihydrate:
0.097 g/100ml (25 °C) [1]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg [2]
Warning
H302, H312 [2]
P280 [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ferrous oxalate (iron(II) oxalate) refers to inorganic compounds with the formula FeC2O4(H2O)x where x is 0 or 2. These are yellow compounds. Characteristic of metal oxalate complexes, these compounds tend to be polymeric, hence their low solubility in water.

Contents

Structure

Like other iron oxalates, ferrous oxalates feature octahedral Fe centers. The dihydrate FeC2O4(H2O)2 is a coordination polymer, consisting of chains of oxalate-bridged ferrous centers, each with two aquo ligands. [3]
Fe(C2O4)(H2O)2-chain-from-xtal-2008-CM-3D-balls.png

Reactions

When heated to 120 °C, the dihydrate dehydrates, and the anhydrous ferrous oxalate decomposes near 190 °C. [4] The product of thermal decomposition is a mixture of iron oxides and pyrophoric iron metal, as well as released carbon dioxide, carbon monoxide, and water. [5]

Ferrous oxalates are precursors to iron phosphates, which are of value in batteries. [6]

Natural occurrence

Anhydrous iron(II) oxalate is unknown among minerals as of 2020. However, the dihydrate is known as humboldtine. [7] [8] A related mineral is stepanovite (Na[Mg(H2O)6][Fe(C2O4)3]·3H2O), an unusual example of a naturally-occurring ferrioxalate. [9] [8]

See also

References

  1. "Iron(II) oxalate dihydrate".
  2. 1 2 3 Sigma-Aldrich Co., Iron(II) oxalate dihydrate. Retrieved on 2014-05-03.
  3. Echigo, Takuya; Kimata, Mitsuyoshi (2008). "Single-crystal X-ray diffraction and spectroscopic studies on humboldtine and lindbergite: weak Jahn–Teller effect of Fe2+ ion". Physics and Chemistry of Minerals . 35 (8): 467–475. Bibcode:2008PCM....35..467E. doi:10.1007/s00269-008-0241-7. S2CID   98739882.
  4. Mu, Jacob; Perlmutter, D.D. (1981). "Thermal decomposition of carbonates, carboxylates, oxalates, acetates, formates, and hydroxides". Thermochimica Acta. 49 (2–3): 207–218. Bibcode:1981TcAc...49..207M. doi:10.1016/0040-6031(81)80175-x.
  5. Hermanek, Martin; Zboril, Radek; Mashlan, Miroslav; Machala, Libor; Schneeweiss, Oldrich (2006). "Thermal Behaviour of Iron(II) Oxalate Dihydrate in the Atmosphere of Its Conversion Gases". J. Mater. Chem. 16 (13): 1273–1280. doi:10.1039/b514565a.
  6. Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. (2007). "A multifunctional 3.5 V iron-based phosphate cathode for rechargeable batteries". Nature Materials. 6 (10): 749–753. Bibcode:2007NatMa...6..749E. doi:10.1038/nmat2007. PMID   17828278.
  7. "Humboldtine".
  8. 1 2 "List of Minerals". 21 March 2011.
  9. "Stepanovite".