Iron(II) citrate

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).

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 Y
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 Y
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[1] unstable
Density	1.91 g/cm3
Melting point	decomposes[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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]

See also

• Iron(III) citrate
• Ammonium ferric citrate