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ChemRixv_An [Fe34] Molecular Metal Oxide_Brechin_28th Aug 2019.pdf (2.85 MB)
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submitted on 28.08.2019 and posted on 30.08.2019by Alice Dearle, Daniel Cutler, Hector Fraser, Sergio Sanz, Edward Lee, Sourav Dey, Ismael Diaz-Ortega, Gary Nichol, Hiroyuki Nojiri, Marco Evangelisti, Gopalan Rajaraman, Jürgen Schnack, Leroy Cronin, Euan Brechin
The dissolution of anhydrous iron bromide in a mixture of pyridine and acetonitrile, in the presence of an organic amine, results in the formation of an [Fe34] metal oxide molecule, structurally characterized by alternate layers of tetrahedral and octahedral Fe(III) ions connected by oxide and hydroxide ions. The outer shell of the cage is capped by a combination of pyridine molecules and bromide ions. Magnetic data, measured at temperatures as low as 0.4 K and fields up to 35 T, reveal competing antiferromagnetic exchange interactions; DFT calculations showing that the magnitudes of the coupling constants are highly dependent on both the Fe-O-Fe angles and Fe-O distances. The simplicity of the synthetic methodology, and the structural similarity between [Fe34], iron oxides, previous Fe(III)-oxo cages, and polyoxometalates (POMs), hints that much larger, molecular Fe(III) oxides can be made.