An [Fe^III₃₄] Molecular Metal Oxide

Abstract

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 characterised by alternate layers of tetrahedral and octahedral FeIII ions connected by oxide and hydroxide ions. The outer shell of the complex 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], bulk iron oxides, previous FeIII–oxo cages, and polyoxometalates (POMs), hints that much larger molecular FeIII oxides can be made.

A 3D MOF based on Adamantoid Tetracopper(II) and Aminophosphine Oxide Cages: Structural Features and Magnetic and Catalytic Properties

“…The DSM is known to correctly estimate the exchange couplings in polynuclear clusters, 59 − 61 including very large ones, such as the Fe 34 core. 62 The coordination geometry of the {Cu 4 OCl 6 } core in 2 discloses two slightly different Cu···Cu separations of 3.126 and 3.138 Å in a [4 + 2] configuration. Hence, we attempted to calculate two J constants belonging to these separations.…”