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DeutschChromium(II) oxalate
| Names | |
|---|---|
| IUPAC name Chromium(2+) oxalate | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.011.282 |
PubChem CID | |
| UNII | |
CompTox Dashboard (EPA) | |
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| Properties | |
| Cr(C2O4) | |
| Molar mass | 140.02 g/mol |
| Appearance | light 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.
Preparation
[edit]According to Nikumbh et al., CrC2O4·2H2O 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, which has been characterized by combustion elemental analysis, infrared spectroscopy, thermogravimetric analysis and powder X-ray diffraction.[1] 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. This would be consistent with the structure of other linear polymeric metal(II) oxalates of general formula MC2O4·2H2O (M = Mg, Fe, etc.).[2] 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]
Milburn and Taube have presented data indicating that 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]
References
[edit]- ^ a b 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.
- ^ 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.
- ^ 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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