Chromium(II) oxalate
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| IUPACName = Chromium(2+) oxalate
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|Section1={{Chembox Identifiers
| CASNo = 814-90-4
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = RV83VA978Q
| PubChem = 13147
| ChemSpiderID = 12595
| SMILES = C(=O)(C(=O)[O-])[O-].[Cr+2]
| InChI = 1/C2H2O4.Cr/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2/p-2
| InChIKey = XVHFYNOGAFYRJV-NUQVWONBAE
| StdInChI = 1S/C2H2O4.Cr/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2/p-2
| StdInChIKey = XVHFYNOGAFYRJV-UHFFFAOYSA-L
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|Section2={{Chembox Properties
| Formula = Cr(C2O4)
| MolarMass = 140.02 g/mol
| Appearance = light green crystals
| Density = 2.461 g/cm3
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| Solubility = 126 g/100 mL (0 °C)
| SolubleOther = negligible in alcohol
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|Section3={{Chembox Hazards
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|Section4={{Chembox Related
| OtherCations = Iron(II) oxalate
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Chromium(II) oxalate is an inorganic compound with the chemical formula CrC2O4.
Preparation
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.{{Cite journal| vauthors = Nikumbh AK, Rahman MM, Aware AD |date=1990|title=A study of the thermal decomposition of chromium(II) oxalate dihydrate using direct current electrical conductivity measurements|journal=Thermochimica Acta|language=en|volume=159|pages=109–123|doi=10.1016/0040-6031(90)80099-K}} 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.).{{cite journal | vauthors = Chen XA, Song FP, Chang XA, Zang HG, Xiao WQ | title = A new polymorph of magnesium oxalate dihydrate | journal = Acta Crystallographica Section E | volume = 64 | issue = Pt 7 | pages = m863 | date = June 2008 | pmid = 21202738 | pmc = 2961852 | doi = 10.1107/S1600536808015870 }} 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.
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.{{Cite journal|last1=Milburn|first1=Ronald M.|last2=Taube|first2=Henry | name-list-style = vanc |title=The Reduction of Oxalate by Chromium(Ii)1,2|date=1960|journal=The Journal of Physical Chemistry|language=en|volume=64|issue=11|pages=1776|doi=10.1021/j100840a513|issn=0022-3654}}
References
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{{Chromium compounds}}
{{Oxalates}}
Category:Chromium(II) compounds
Category:Chromium–oxygen compounds
{{Inorganic-compound-stub}}