Ferric oxalate

The coordination complex with the formula [Fe(C2O4)3]3- forms a variety of salts, a well-known example being potassium ferrioxalate.

Mössbauer spectrum of Fe2(C2O4)3 · 4 H2O exhibits an isomer shift of 0.38 mm/s and a quadrupole splitting of 0.40 mm/s, suggesting a high spin Fe3+ in octahedral coordination.

Ferric oxalate tetrahydrate has been investigated as a possible cheap material for the positive electrode of lithium-iron batteries.

It can intercalate lithium ions at an average potential of 3.35 V, and has shown a sustainable capacity of 98 mAh/g.

[1] Ferric oxalate hexahydrate is used with sodium borohydride for radical Markovnikov hydrofunctionalization reactions of alkenes.

Structure of hydrated ferric oxalate Color code: red=O, white = H, blue = Fe, gray = C.
Room temperature Mössbauer spectrum of Fe 2 (C 2 O 4 ) 3 ·4H 2 O