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Thin films with a stoichiometry of CeFeOx were conformally deposited on high-surface-area γ-Al2O3 by Atomic Layer Deposition (ALD). X-ray diffraction (XRD) patterns, High-Resolution Transmission Electron Microscopy (HRTEM) images, Raman spectra, and Mössbauer spectra demonstrated that 2 nm-thick films exhibited a perovskite structure after reduction at 1073 K but converted to a fluorite phase upon oxidation at 1073 K. The transition between the fluorite and perovskite structures was reversible for at least five oxidation and reduction cycles. Coulometric titration at 1073 K showed that reduction of the fluorite phase occurred in two steps, one at a P(O2) of 10−15 atm and a second at a P(O2) of 10−8 atm. X-ray Photoelectron Spectra (XPS) demonstrated that Ce has +3 valence in the perovskite phase and +4 valence in the fluorite phase, while Fe is mixed +2 and +3 valence in the reduced perovskite phase and +3 valence in the fluorite phase. The CeFeOx thin films were found to retain high surface area and remain conformal to the γ-Al2O3 support upon redox cycling suggesting that they may be useful in applications ranging from catalysis to spintronics. [ABSTRACT FROM AUTHOR]

The simple replacement of H2O with D2O in the synthesis of a solid-state manganese complex results in a new structurally and magnetically distinct phase. The three types of experiments described here indicate that changing the hydrogen isotope can have a significant effect on the structural and physical properties of metal aggregates formed in aqueous solutions.

The hexanuclear iron(III) complex (Fe3O(OAc)6(H2O)3)(Fe6(O)2(O2)3(OAc)9).8H2O was synthesized from (Fe6(O)2(O2)(OAc)9)- and characterized by Mossbauer, Raman, x-ray crystallographic methods. The complex, which features an elongated O-O bond, contains two antiferromagnetically coupled (Fe3O)7+ groups arranged in a face-to-face geometry and bridged by eta2-mu2-acetates and eta2-mu2-peroxo ligands.

Use of the triiron precursors (Fe3O(O2CPh)6(H2O)2(MeCn)) and (Fe3O(O2CPh)6(Me2O)3(O2CPh)) helps prepare polyiron complexes of general formula (Fe16MO10(OH)10(O2CPh)20), where M is Mn, Fe or Co in modest yields. Single-crystal X-ray studies help study the structures of these complexes and low-temperature Mossbauer and magnetic studies suggest that the complex straddles the molecular/solid-state boundary. Decrease in magnetic moment at low temperatures reveals the existence of antiferromagnetic interactions in the complexes.

Synthesis and study of a polyiron oxo complex reveals the presence of an intervalence charge transfer band that is antiferromagnetically exchange-coupled. The band has a Mossbauer time scale valence-localization and Mossbauer spectral properties in accord with superparamagnetism. The properties resemble that of iron storage protein ferritin's mineral core.

The decanuclear iron (III) molecular ferric wheel complex, (Fe(OMe)2(O2CCH2Cl))10 results due to methanolysis of iron monochloroacetate and ferric nitrate. A previously unknown circular ring structure occurs due to geometry-induced convex and concave curvatures. The circular structure does not significantly affect the Mossbauer and geometric properties of the individual iron sites in the complex.

Analyses of four complexes with cubic(M4(OR)4)n+ cores involved their synthesis and crystallographic characterization. The complexes are (Mn4(OEt)4(EtOH)2(DPM)4), (FeIIIFe (super II)(sub 3) (OMe)5(MeOH)3(OBz)4), (Fe(OMe)(MeOH)(DBM))4 and Fe((OMe)MeOH)(DPM)4. Various structural, physical and electronic attributes are evident for these iron and manganese alkoxide cubes.

A novel polyiron oxo complex, [Fe.sup.III.sub.4][Fe.sup.II.sub.8][(O).sub.2] [([OCH.sub.3]).sub.18] [([O.sub.2][CCH.sub.3]).sub.6][([CH.sub.3]OH).sub.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 Mossbauer 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., Ion homeostasis is maintained in part by the iron storage protein ferritin (Ft), which is comprised of a highly symmetrical coat consisting of 24 polypeptide subunits that can encapsulate up [...]

A study was conducted on the interaction of Fe2+ and phosphate in bacterial ferritin from Azotobacter vinelandii (AVBF). Results show that phosphate sponsors the site of interaction of Fe2+ with the mineral core of AVBF. Further observations also suggest that the bound Fe2+ experiences a reversible electron-transfer reaction with the mineral core irons which results in the formation of 57Fe3+.

Bis-macrocyclic FeII/FeII complex is electrochemically oxidized to form a mixed valence FeII/FeII compound. Electronic interaction is facilitated by a delocalized Pi-system of binucleating ligand. Mossbauer spectrum of the mixed valence complex consists of a single, quadrupole-split doublet, showing the equivalence of two iron atoms.