Iron(II) citrate

Iron(II) citrate
	; Skeletal formula of iron(II) citrate
	; Powdered Iron(II) citrate hydrate
Names
	IUPAC name Iron(II) hydrogen 2-hydroxy-1,2,3-tricarboxylpropane
	Other names Iron(II) citrate, Ferrous citrate, Iron citrate
Identifiers
CAS Number	hydrogen citrate: 22242-53-1 ;
3D model (JSmol)	hydrogen citrate: Interactive image;
ChemSpider	hydrogen citrate: 9239835;
ECHA InfoCard	100.041.463
EC Number	hydrogen citrate: 245-625-1;
PubChem CID	hydrogen citrate: 11064683;
UNII	hydrogen citrate: 33KM3X4QQW ;
	InChI InChI=1S/C6H8O7.Fe/c7-3(8)1-6(13,5(11)12)2-4(9)10;/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);/q;+2/p-2 Key: APVZWAOKZPNDNR-UHFFFAOYSA-L;
	SMILES hydrogen citrate: C(C(=O)O)C(CC(=O)[O-])(C(=O)[O-])O.[Fe+2];
Properties
Chemical formula	FeC6H6O7
Molar mass	245.95644 g/mol
Appearance	slightly gray-green powder or white crystals unstable
Density	1.91 g/cm3
Melting point	decomposes
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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⁺{[Fe(C₆H₅O₇)(H₂O)]⁻}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.^[3] Ferrous citrates are all paramagnetic, reflecting the weak crystal field of the carboxylate ligands.^[4]

Structure of the anionic coordination polymer {[Fe(C₆H₅O₇)(H₂O)]⁻}_n.^[3] (legend: red = O, gray = C, blue = Fe, white = H).

Ferrous citrates are produced by treating disodium citrate Na
₂C
₆H
₆O
₇ with sources of iron(II) aquo complexes, such as iron(II) sulfate.^[5]^[2] Ferrous citrates are all highly unstable in air, converting to ferric citrates.

It is a nutrient supplement approved by the FDA.^[6]^[7]

References

^ Food Chemicals Codex. United States Pharmacopeial Convention. 2010. p. 396. ISBN 978-1-889788-86-9.
^ ^a ^b Perry, Dale L.; Phillips, Sidney L., eds. (1995). Handbook of Inorganic Compounds. Boca Raton, Florida: CRC Press. p. 167. ISBN 0-8493-8671-3.
^ ^a ^b Strouse, Jane; Layten, Steven W.; Strouse, Charles E. (1977). "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. doi:10.1021/ja00444a041. PMID 830693.
^ Pierre, J. L.; Gautier-Luneau, I. (2000). "Iron and Citric Acid: A Fuzzy Chemistry of Ubiquitous Biological Relevance". Biometals. 13 (1): 91–96. doi:10.1023/A:1009225701332. PMID 10831230. S2CID 2301450.
^ "CFR - Code of Federal Regulations Title 21". www.fda.gov. U.S. Food and Drug Administration. 2013-06-01. Retrieved 2014-08-02.
^ PubChem. "Iron(II) citrate". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-08-22.
^ "Substances Added to Food (formerly EAFUS)". www.cfsanappsexternal.fda.gov. Retrieved 2022-08-22.

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[1] Food Chemicals Codex. United States Pharmacopeial Convention. 2010. p. 396. ISBN 978-1-889788-86-9.

[hpic-2] Perry, Dale L.; Phillips, Sidney L., eds. (1995). Handbook of Inorganic Compounds. Boca Raton, Florida: CRC Press. p. 167. ISBN 0-8493-8671-3.

[Strouse-3] Strouse, Jane; Layten, Steven W.; Strouse, Charles E. (1977). "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. doi:10.1021/ja00444a041. PMID 830693.

[4] Pierre, J. L.; Gautier-Luneau, I. (2000). "Iron and Citric Acid: A Fuzzy Chemistry of Ubiquitous Biological Relevance". Biometals. 13 (1): 91–96. doi:10.1023/A:1009225701332. PMID 10831230. S2CID 2301450.

[fda-5] "CFR - Code of Federal Regulations Title 21". www.fda.gov. U.S. Food and Drug Administration. 2013-06-01. Retrieved 2014-08-02.

[6] PubChem. "Iron(II) citrate". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-08-22.

[7] "Substances Added to Food (formerly EAFUS)". www.cfsanappsexternal.fda.gov. Retrieved 2022-08-22.

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See also

References