Keynote Lecture
Understanding Ferric Citrate

Ferric Citrate is a common name of a vareity of substances having different structures and iron/citrate ratios. Some of these materials play an important role in biology, madicine and food industry despite the fact that their molecular structure is virtually unknown. In the last two decades we have ilucidated the strucure of several iron(III) citrate complexes, all of which are polynuclear and contain different iron/citrate ratio. One complex, namely [Fe₂Cit₂(H₂O)₂]^2- , is recognized and transferred through cell membranes by a specific protein. Ferric Ammonium Citrate is used extensively in medicine as an immaging contrast agent and to treat iron-deficiency anemia. It is also used as an additive in the food industry but its structure and composition remains unknown. We have systematically crystallized species present in the commercial material and present here the molecular structure of the predominent component, a new trinuclear ferric citrate complex.