Chromium(II) oxalate is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the chemical formula CrC₂O₄.

Preparation

According to Nikumbh et al., CrC₂O₄·2H₂O can be prepared from

chromium(II) sulfate Chromium(II) sulfate refers to inorganic compounds with the chemical formula CrSO4·n H2O. Several closely related water of crystallization, hydrated salts are known. The pentahydrate is a blue solid that dissolves readily in water. Solutions of ...

pentahydrate by reaction with a mixture of sodium oxalate and

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...

in degassed aqueous solution, forming a light green crystalline product, which has been characterized by combustion

elemental analysis Elemental analysis is a process where a sample of some material (e.g., soil, waste or drinking water, bodily fluids, minerals, chemical compounds) is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualita ...

, infrared spectroscopy, thermogravimetric analysis and

powder X-ray diffraction Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is cal ...

. The measured magnetic moment of 4.65

B.M. Bachelor of Music (BM or BMus) is an academic degree awarded by a college, university, or conservatory upon completion of a program of study in music. In the United States, it is a professional degree, and the majority of work consists of prescr ...

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.). 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.

References

Chromium(II) compounds Oxalates Chromium–oxygen compounds {{Inorganic-compound-stub