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Synthesis, structure, magnetic anisotropy and slow magnetic relaxation of two air-stable Co(iii)–Co(ii) mixed-valence complexes with a five-coordinated Co(ii) centre were studied by single-crystal X-ray crystallography, magnetometry and HFEPR.

Recently, the choice of ligand and geometric control of mononuclear complexes, which can affect the relaxation pathways and blocking temperature, have received wide attention in the field of single-ion magnets (SIMs). To find out the influence of the coordination environment on SIMs, two four-coordinate mononuclear Co(II) complexes [NEt

The high demand for electronic components from limited natural resources is forcing manufacturers to focus on thin-film technology but they are facing problems - limits of operation, uniformity of the films and expensive manufacturing tools. Chemistry can provide solutions to the last two problems with ease of manufacture and uniformity of two-dimensional materials retaining all functionalities within one single layer. Here, we present one such layered compound, [CoII(terpy)(H2O)2@CoII2(µ2-H2O)3{IrIII(ppy-COO)3}2]·6H2O (1). Each charge-balanced layer is an anionic triple-ply holding [CoII(terpy)(H2O)2]2+ cations. Treating the crystals with warm acetone or by sonication breaks the weak interlayer supramolecular π-π and H-bonds leading to free standing single- and double layers (>30´30 µm2). Each CoII(terpy)(H2O)2, at crystallographic positions 14.5 Å apart, behaves as a single-ion magnet (SIM). This is the first observation of periodic positioning of SIM shielded from their neighbours amounting to a staggering 350´1012 CoII/in2 capable of functioning as a 350 TeraBit/in2 magnetic memory device.

An octacoordinated Fe(II) complex, [FeII(dpphen)2](BF4)2·1.3H2O (1; dpphen = 2,9-bis(pyrazol-1-yl)-1,10-phenanthroline), with a pseudo-D2d-symmetric metal center has been synthesized. Magnetic, high-frequency/-field electron paramagnetic resonance (HF-EPR), and theoretical investigations reveal that 1 is characterized by uniaxial magnetic anisotropy with a negative axial zero-field splitting (ZFS) (D ≈ -6.0 cm-1) and a very small rhombic ZFS (E ≈ 0.04 cm-1). Under applied dc magnetic fields, complex 1 exhibits slow magnetic relaxation at low temperature. Fitting the relaxation time with the Arrhenius mode combining Orbach and tunneling terms affords a good fit to all the data and yields an effective energy barrier (17.0 cm-1) close to the energy gap between the ground state and the first excited state. The origin of the strong uniaxial magnetic anisotropy for 1 has been clearly understood from theoretical calculations. Our study suggests that high-coordinated compounds featuring a D2d-symmetric metal center are promising candidates for mononuclear single-molecule magnets.

Magnetic anisotropy is the key element in the construction of single-ion magnets, a kind of nanomagnets for high-density information storage. This works describes an unusual large easy-plane magnetic anisotropy (with a zero-field splitting parameter D of +40.2 cm-1 ), mainly arising from the second-order spin-orbit coupling effect in a trigonal-planar CoII complex [Li(THF)4 ][Co(NPh2 )3 ], revealed by combined studies of magnetism, high frequency/field electron paramagnetic resonance spectroscopy, and ab initio calculations. Meanwhile, the field-induced slow magnetic relaxation in this complex was mainly attributed to the Raman process.

The coordination geometries of the Co(ii) site in the two complexes [Co(imidazole)

The largest Ln-Fe metal cluster [Gd

The reaction of the multisite coordination ligand (H

Three Fe(iii) dimers, [Fe

A yellow crystal with {FeII4O4} cubes is modified to a black crystal with {FeIII4O4} cubes via a SC–SC transformation., The very rare occurrence of a gas–solid chemical reaction has been found to take place on a molecule within a compact non-porous crystal without destroying its long-range structural order and retaining similar crystal structures when yellow crystals of FeII4(mbm)4Cl4(MeOH)4 were exposed to air to give black [FeIII4(mbm)4Cl4(OH)4]·2H2O. The latter cannot be synthesised directly. The original cluster underwent an exchange of methanol to hydroxide, an oxidation of Fe(ii) to Fe(iii), a change in stereochemistry and hydration while the packing and space-group remained unaltered.

Magnetic anisotropy is the key element in the construction of single-ion magnets, a kind of nanomagnets for high-density information storage. This works describes an unusual large easy-plane magnetic anisotropy (with a zero-field splitting parameter D of +40.2 cm