Chromium(II) oxalate

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Chromium(II) oxalate
Names
IUPAC name
Chromium(2+) oxalate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.011.282 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C2H2O4.Cr/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2/p-2
    Key: XVHFYNOGAFYRJV-UHFFFAOYSA-L
  • InChI=1/C2H2O4.Cr/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2/p-2
    Key: XVHFYNOGAFYRJV-NUQVWONBAE
  • C(=O)(C(=O)[O-])[O-].[Cr+2]
Properties
Cr(C2O4)
Molar mass 140.02 g/mol
Appearancelight green crystals
Density 2.461 g/cm3
126 g/100 mL (0 °C)
Solubility negligible in alcohol
Related compounds
Other cations
Iron(II) oxalate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chromium(II) oxalate is an inorganic compound with the chemical formula CrC2O4. A light green dihydrate exists.

Contents

Structure

The measured magnetic moment of 4.65 B.M. suggests that the chromium ion does not form a Cr-Cr bond and has a high-spin octahedral coordination geometry. [1] This would be consistent with the structure of other linear polymeric metal(II) oxalates of general formula MC2O4·2H2O (M = Mg, Fe, etc.). [2]

Preparation

The dihydrate can be prepared from chromium(II) sulfate pentahydrate by reaction with a mixture of sodium oxalate and oxalic acid in degassed aqueous solution, forming a light green crystalline product. [1]

A study found chromium(II) will reduce oxalate to glycolate within a few minutes in acidic aqueous solutions, casting some doubt on the formulation of chromium(II) oxalate as a stable Cr2+ species if prepared from acidic aqueous solutions. [3]

Reactions

The dihydrate loses water to form anhydrous CrC2O4 when heated above 140 °C in an inert atmosphere. Heating above 320 °C produces a mixture of chromium oxides. [1]

References

  1. 1 2 3 Nikumbh AK, Rahman MM, Aware AD (1990). "A study of the thermal decomposition of chromium(II) oxalate dihydrate using direct current electrical conductivity measurements". Thermochimica Acta. 159: 109–123. doi:10.1016/0040-6031(90)80099-K.
  2. ↑ Chen XA, Song FP, Chang XA, Zang HG, Xiao WQ (June 2008). "A new polymorph of magnesium oxalate dihydrate". Acta Crystallographica Section E. 64 (Pt 7): m863. doi:10.1107/S1600536808015870. PMC   2961852 . PMID   21202738.
  3. ↑ Milburn RM, Taube H (1960). "The Reduction of Oxalate by Chromium(Ii)1,2". The Journal of Physical Chemistry. 64 (11): 1776. doi:10.1021/j100840a513. ISSN   0022-3654.


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