Iron(II) citrate explained

Ferrous citrate, also known as iron(II) citrate or iron(2+) citrate, describes coordination complexes containing citrate anions with Fe²⁺ formed in aqueous solution. Although a number of complexes are possible (or even likely), only one complex has been crystallized. That complex is the coordination polymer with the formula [Fe(H₂O)₆]²⁺₂^.2H₂O, where C₆H₅O₇^3- is HOC(CH₂CO₂⁻)₂(CO₂⁻, i.e., the triple conjugate base of citric acid wherein the three carboxylic acid groups are ionized.^[1] Ferrous citrates are all paramagnetic, reflecting the weak crystal field of the carboxylate ligands.^[2]

Ferrous citrates are produced by treating disodium citrate with sources of iron(II) aquo complexes, such as iron(II) sulfate.^[3] Ferrous citrates are all highly unstable in air, converting to ferric citrates.

It is a nutrient supplement approved by the FDA.^{[4] [5]}

See also

• Iron(III) citrate
• Ammonium ferric citrate

Notes and References

1. 10.1021/ja00444a041. 830693. Structural Studies of transition metal complexes of triionized and tetraionized citrate. Models for the coordination of the citrate ion to transition metal ions in solution and at the active site of aconitase. Journal of the American Chemical Society. 99. 2. 562–572. 1977. Strouse. Jane. Layten. Steven W.. Strouse. Charles E..
2. 10.1023/A:1009225701332. 2000. Pierre. J. L.. Biometals. Iron and Citric Acid: A Fuzzy Chemistry of Ubiquitous Biological Relevance. 13. 91–96. Gautier-Luneau. I.. 1. 10831230. 2301450.
3. Web site: CFR - Code of Federal Regulations Title 21. www.fda.gov. 2013-06-01. 2014-08-02. U.S. Food and Drug Administration.
4. Web site: PubChem . Iron(II) citrate . 2022-08-22 . pubchem.ncbi.nlm.nih.gov . en.
5. Web site: Substances Added to Food (formerly EAFUS) . 2022-08-22 . www.cfsanappsexternal.fda.gov . en-US.