Iron(III) acetate

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Iron(III) acetate[1]
IUPAC name
iron(III) acetate
Other names
basic iron(III) acetate , iron(III) oxyacetate, iron(III) Acetate
3D model (Jmol)
ECHA InfoCard 100.030.838
Molar mass 650.9 g/mol
Appearance brownish-red amorphous powder
Solubility soluble in ethanol[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Ferric acetate is the coordination compound more commonly known as "basic iron acetate". With the formula [Fe3O(OAc)6(H2O)3]OAc (OAc is CH3CO2), it is a salt, composed of the cation [Fe3(μ3-O)(OAc)6(H2O)3]+ and an acetate anion.[3] The formation of the red-brown complex has long been used as a test for ferric ions.[4]

Structure and synthesis[edit]

Basic iron acetate forms on treating aqueous solutions of iron(III) sources with acetate salts.[5] Solid iron may be mixed with hydrogen peroxide to form iron(II and/or III) hydroxide, which can then react with vinegar/acetic acid or acetate salts to form iron(III) acetate.

Early work showed that it is trinuclear.[6] The Fe centres are equivalent, each being octahedral, being bound to six oxygen ligands, including a triply bridging oxide at the center of the equilateral triangle.[7] The compound was an early example of a molecular compound of iron that features an oxide ligand. Ignoring its 24 hydrogen centres, the cation has D3h symmetry.


The terminal aqua ligands on the trimetallic framework can be substituted with other ligands, such as pyridine and dimethylformamide. Many different salts are known by exchanging the anion, e.g. [Fe33-O)(OAc)6(H2O)3]Cl. Reduction of the cation affords the neutral mixed-valence derivative that contains one ferrous and two ferric centers.[3] Mixed metal species are known such as [Fe2CoO(OAc)6(H2O)3].[8]

Related compounds[edit]

Chromium(III), ruthenium(III), vanadium(III), and rhodium(III) form analogous compounds.[9] Iron(III) acetate (lacking the oxo ligand) has been claimed as a red coloured compound from the reaction of silver acetate and iron(III) chloride.[10]


Materials prepared by heating iron, acetic acid, and air, loosely described as basic iron acetates, are used as dyes and mordants.[3]


  1. ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. pp. 4–63. ISBN 0-8493-0487-3. 
  2. ^ "Iron(III) Acetate". EndMemo. Retrieved 2015-04-18. 
  3. ^ a b c J., Burgess; M. V., Twigg (2005). R. Bruce, King; J., Wiley, eds. Encyclopedia of inorganic chemistry (2nd ed.). New York: Wiley. ISBN 978-0-470-86078-6. 
  4. ^ H., Brearley; F., Ibbotson (1902). The Analysis of Steel-Works Materials. London ; New York: Longmans, Green. 
  5. ^ W., Simon. Manual of Chemistry. p. 474. ISBN 1406733350. 
  6. ^ Weinland, R.; Dinkelacker, P. (July 1909). "Über Salze einer Hexaacetato(formiato)-trichrombase. II". Berichte der deutschen chemischen Gesellschaft. 42 (3): 2997–3018. doi:10.1002/cber.19090420318. 
  7. ^ Figgis, B. N.; Robertson, G. B. (13 February 1965). "Crystal-Molecular Structure and Magnetic Properties of Cr3(CH3.COO)6OCl.5H2O". Nature. 205 (4972): 694–695. doi:10.1038/205694a0.  This paper describes the isostructure chromium and iron compounds.
  8. ^ Blake, Antony B.; Yavari, Ahmad; Hatfield, William E.; Sethulekshmi, C. N. (1985). "Magnetic and spectroscopic properties of some heterotrinuclear basic acetates of chromium(III), iron(III), and divalent metal ions". Journal of the Chemical Society, Dalton Transactions (12): 2509. doi:10.1039/DT9850002509. 
  9. ^ Holleman, A. F.; Wiberg, E. (2001), Inorganic Chemistry, San Diego: Academic Press, ISBN 0-12-352651-5 
  10. ^ Paul, Ram C.; Narula, Ramesh C.; Vasisht, Sham K. (December 1978). "Iron(III) acetates". Transition Metal Chemistry. 3 (1): 35–38. doi:10.1007/BF01393501.