Potassium ferrooxalate

Potassium ferrooxalate
Names
IUPAC name Potassium iron(II) oxalate
Other names potassium ferrooxalate potassium bisoxalatoferrate(II)
Identifiers
CAS Number	28288-62-2^Y
3D model (JSmol)	Interactive image
InChI InChI=1S/2C2H2O4.Fe.2K/c23-1(4)2(5)6;;;/h2(H,3,4)(H,5,6);;;/q;;+2;2*+1/p-4 Key: LDRXJDFKHOUYMS-UHFFFAOYSA-J
SMILES [K+].[K+].O=C(-C(=O)O1)O[Fe-2]12OC(-C(=O)O2)=O
Properties
Chemical formula	K ₂[Fe(C ₂O ₄) ₂] (anhydrous) K ₂[Fe(C ₂O ₄) ₂]·2H ₂O (dihydrate)
Appearance	orange-yellow solid (anhydrous), golden-yellow crystals (dihydrate) ^[1]
Melting point	decomposes at 470 °C ^[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Potassium ferrooxalate, also known as potassium bisoxalatoferrate(II), is a salt with the formula K₂Fe(C₂O₄)₂(H₂O)_x. The anion is a transition metal oxalate complex, consisting of an atom of iron in the +2 oxidation state bound to oxalate (C
₂O²⁻
₄) ligands and water.^[2]

Anhydrous K₂Fe(C₂O₄)₂ has been prepared by hydrothermal methods from ferrous chloride. It is a coordination polymer with trigonal prismatic Fe(C₂O₄)₃ centers. Half of the oxalate ligands are bridging.^[3]

Dihydrate

The material K₂Fe(C₂O₄)₂(H₂O)₂ has been claimed^[1] but not verified.Potassium ferrooxalate is believed to be formed when the related compound potassium ferrioxalate K
₃[Fe(C
₂O
₄)
₃] is decomposed by light in solution (a common method of actinometry) or heated above 296 °C.^[1] The anhydrous salt is orange-yellow and dissolves in water to give a red solution. Crystals of the dihydrate K
₂[Fe(C
₂O
₄)
₂]·2H
₂O are golden yellow in color.^[1]

References

^ ^a ^b ^c ^d ^e J. Ladriere (1992): "Mössbauer study on the thermal decomposition of potassium tris (oxalato) ferrate(III) trihydrate and bis (oxalato) ferrate(II) dihydrate". Hyperfine Interactions, volume 70, issue 1, pages 1095–1098. doi:10.1007/BF02397520
^ Amanchar, Sara; Schweitzer, Thierry; Mazet, Thomas; Malaman, Bernard; Diop, Leopold V. B.; Francois, Michel (2023). "Structure of the new iron(II) oxalate potassium salt K₂Fe[(C₂O₄)₂(H₂O)₂]·0.18H₂O". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials. 79 (4): 263–270. doi:10.1107/S2052520623004602. PMID 37347140. S2CID 259223071.
^ Hursthouse, Michael B.; Light, Mark E.; Price, Daniel J. (2004). "One-Dimensional Magnetism in Anhydrous Iron and Cobalt Ternary Oxalates with Rare Trigonal-Prismatic Metal Coordination Environment". Angewandte Chemie International Edition. 43 (4): 472–475. doi:10.1002/anie.200352406. PMID 14735538.