Chromium(II) oxalate

Chromium(II) oxalate is an inorganic compound with the chemical formula CrC2O4.

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. Their light green crystalline product was characterized by combustion elemental analysis, infrared spectroscopy, thermogravimetric analysis and powder X-ray diffraction. 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 2+ oxalates of general formula MC2O4.2H2O, where M = Mg2+, Fe2+, etc. The chromium (II) dihydrate forms the 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.

References

A. K. Nikumbh, M.M. Rahman and A.D. Aware, Thermochimica Acta, 159 (1990) 109-123.

R. M. Milburn, and H. Taube, J. Phys. Chem., 1960, 64 (11), pp 1776–1776.

Xue-An Chen, Fang-Ping Song, Xin-An Chang, He-Gui Zanga and Wei-Qiang Xiao Acta Cryst. E64, 2008, m863.

https://en.wikipedia.org/wiki/Iron(II)_oxalate

Category:Chromium(II) compounds
Category:Oxalates
Category:Chromium–oxygen compounds