title: A mixed-valent polyiron oxo complex that models the biomineralization of the ferritin core.
abstract: A novel polyiron oxo complex, [FeIII4FeII8(O)2(OCH3)18(O2CCH3)6(CH3OH) 4.67] (1), has been prepared from ferrous acetate and lithium methoxide in methanol by slow addition of dioxygen. The three-dimensional close-packed layered structure found in 1 closely mimics that proposed for the inorganic core in the iron storage protein ferritin. The Mössbauer spectra of 1 reveal superparamagnetic relaxation at temperatures below 15 K, a property characteristic of the ferritin core. The small size and mixed-valent nature of 1 suggest that it is a reasonable model for intermediates formed in the biomineralization of iron during ferritin core formation. A related compound, with the same iron-oxygen framework found in 1 but containing only two ferric ions, has also been structurally characterized. Because the clusters exhibit properties of both discrete molecules and extended solids, they are representative of a new class of nanometer-sized compounds that bridge the molecular solid-state boundary.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: K L
authors.initials: KL
authors.lastname: Taft
authors.forename: G C
authors.initials: GC
authors.lastname: Papaefthymiou
authors.forename: S J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D000818:Animals; D005293:Ferritins / Q000737:chemistry / Q000648:ultrastructure*; D006736:Horses; D006801:Humans; D066298:In Vitro Techniques; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D013057:Spectrum Analysis
chemical_list: D005293:Ferritins; D007501:Iron