Spin-Phonon Coupling and Slow-Magnetic Relaxation in Pristine Ferrocenium.

We report the spin dynamic properties of non-substituted ferrocenium complexes. Ferrocenium shows a field-induced single-molecule magnet behaviour in DMF solution while cobaltocene lacks slow spin relaxation neither in powder nor in solution. Multireference quantum mechanical calculations give a non-Aufbau orbital occupation for ferrocenium with small first excitation energy that agrees with the relatively large measured magnetic anisotropy for a transition metal S=1/2 system.

Magnetic anisotropy in Yb complex candidates for molecular qubits: a theoretical analysis.

The magnetic properties of mononuclear YbIII complexes have been explored by using multiconfigurational CASPT2/RASSI calculations. Such complexes, in particular the case of [Yb(trensal)] complex, have been proposed as molecular qubits due to their spin dynamics properties. We have verified the accuracy of the theoretical approach to study such systems by comparing with experimental magnetic data.

[UF ] : A Molecular Hexafluorido Actinide(IV) Complex with Compensating Spin and Orbital Magnetic Moments.

The first structurally characterized hexafluorido complex of a tetravalent actinide ion, the [UF ] anion, is reported in the (NEt ) [UF ]⋅2 H O salt (1). The weak magnetic response of 1 results from both U spin and orbital contributions, as established by combining X-ray magnetic circular dichroism (XMCD) spectroscopy and bulk magnetization measurements. The spin and orbital moments are virtually identical in magnitude, but opposite in sign, resulting in an almost perfect cancellation, which is corroborated by ab initio calculations.

Magnetization Slow Dynamics in Ferrocenium Complexes.

The single-molecule magnet (SMM) properties of a series of ferrocenium complexes, [Fe(η -C R ) ] (R=Me, Bn), are reported. In the presence of an applied dc field, the slow dynamics of the magnetization in [Fe(η -C Me ) ]BAr are revealed. Multireference quantum mechanical calculations show a large energy difference between the ground and first excited states, excluding the commonly invoked, thermally activated (Orbach-like) mechanism of relaxation.

Slow-spin relaxation of a low-spin S = 1/2 Fe carborane complex.

In this communication, we report the first evidence of slow-spin relaxation of a low-spin FeIII carborane complex. Iron S = 1/2 complexes showing such behaviour are particularly appealing as qubit candidates because they fulfil some of the main requirements to reach long decoherence times, such as moderate magnetic anisotropy, small spin, metal element mainly with zero-nuclear spin and furthermore, large versatility to introduce chemical modifications.

Mononuclear Lanthanide Complexes with 18-Crown-6 Ether: Synthesis, Characterization, Magnetic Properties, and Theoretical Studies.

A family of lanthanide metal complexes with the general formula [Ln(HO)(18-crown-6)](ClO) (Ln = Tb, Dy, Er, and Yb) has been synthesized. Their magnetic properties have been characterized by direct- and alternating-current SQUID measurements and analyzed with the help of CASSCF-type calculations. The Dy and Yb compounds show slow relaxation of magnetization under an external magnetic field.

Predetermined Ferromagnetic Coupling via Strict Control of M-O-M Angles.

An imidazolidine-phenolate ligand HL yields quadruple-bridged (μ-NCN)(μ-O) ferromagnetic dinuclear nickel and cobalt complexes. Both kinds of bridges contribute to the ferromagnetic coupling, but the ferromagnetism of these samples is mainly ascribed to the double μ-O links, on the basis of density functional theory calculations. These studies demonstrate not only that the short M-O-M angles of the MO cores favors the parallel alignment of the electrons but also that these angles are the optimal ones for maximizing the ferromagnetic contribution in these complexes.

A Low Spin Manganese(IV) Nitride Single Molecule Magnet.

Structural, spectroscopic and magnetic methods have been used to characterize the tris(carbene)borate compound PhB(MesIm)Mn≡N as a four-coordinate manganese(IV) complex with a low spin ( = 1/2) configuration. The slow relaxation of the magnetization in this complex, i.e.