Ferrous oxalate (iron(II) oxalate) refers to inorganic compounds with the formula FeC2O4(H2O)x where x is 0 or 2. These are orange compounds. Characteristic of metal oxalate complexes, these compounds tend to be polymeric, hence their low solubility in water.

Structure and reactions

Like other iron oxalates, ferrous oxalates feature octahedral Fe centers. The dihydrate FeC2O4(H2O)x is a coordination polymer, consisting of chains of oxalate-bridged ferrous centers, each with two aquo ligands.[3]
Ball-and-stick model of a chain in the crystal structure of iron(II) oxalate dihydrate

When heated to 120 °C, the dihydrate dehydrates, and the anhydrous ferrous oxalate decomposes near 190 °C.[4] The products 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, although much more complex mineral is stepanovite,
Na[Mg(H2O)6] [Fe3+(C2O4)3]·3H2O is an unusual example of a naturally-occurring ferrioxalate.[9][8]

See also

References

  1. ^ "Iron(II) oxalate dihydrate".
  2. ^ a b c 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. ^ a b "List of Minerals". 21 March 2011.
  9. ^ "Stepanovite".
Allikas: https://en.wikipedia.org/wiki/Ferrous_oxalate
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