AbstractThe reduction of UVI uranyl halides or amides with simple LnII or UIII salts forms highly symmetric, linear, oxo-bridged trinuclear UV/LnIII/UV, LnIII/UIV/LnIII, and UIV/UIV/UIV complexes or linear LnIII/UV polymers depending on the stoichiometry and solvent. The reactions can be tuned to give the products of one- or two-electron uranyl reduction. The reactivity and magnetism of these compounds are discussed in the context of using a series of strongly oxo-coupled homo- and heterometallic poly(f-block) chains to better understand fundamental electronic structure in the f-block.

The magnetic properties of the 5f5 [tris-(tri-1-pyrazolylborato)–plutonium(III)] complex have been investigated by ac susceptibility measurements, showing it to be the first plutonium single-molecule magnet; its magnetic relaxation slows down with decreasing temperature through a thermally activated mechanism followed by a quantum tunnelling regime below 5 K.

Syntheses of the bimetallic uranium(III) and neptunium(III) complexes [(UI)2(L)], [(NpI)2(L)], and [{U(BH4)}2(L)] of the Schiff-base pyrrole macrocycles L are described. In the absence of single-crystal structural data, fitting of the variable-temperature solid-state magnetic data allows the prediction of polymeric structures for these compounds in the solid state.

Inelastic neutron scattering, probing the temporal spin–spin correlation at the microscopic scale, is a powerful technique to study the magnetic behaviour of molecular nanomagnets. Experiments at different energy scales and different energy-transfer resolution allow precise determinations of the parameters defining the effective Hamiltonians used to model the diverse physical properties exhibited by this class of materials. The intrinsic disadvantage of the technique (low flux, requiring a sample mass in the gram scale) is over-compensated by the large amount of information that can be straightforwardly extracted. Zero-field splittings and exchange interactions can be determined with a large degree of confidence, shedding light on important issues such as magnetization tunnelling in giant-spin clusters, or the occurrence of quantum coherence phenomena and their consequences on macroscopic observables.Inelastic neutron scattering allows precise determinations of the parameters defining the effective Hamiltonians used to model the physical properties of molecular nanomagnets. This paper reviews the results of selected experiments addressing the tunnelling of the magnetization in giant-spin clusters and the occurrence of quantum coherence phenomena in ring-shaped molecules.

The ground-state symmetries of Np ions in the low temperature phase of NpO2 are discussed with reference to the results of resonant X-ray scattering experiments suggesting the occurrence of long-range multipolar order with electric quadrupole secondary order parameter. Two models have been proposed in the literature: one based on a Γ4 doublet (in D3dD3d point group), the other on a Γ5 (Γ6) singlet. We show, through a theoretical group analysis, that the Γ4 doublet is not compatible with the available experimental data. Our analysis supports the hypothesis of a singlet ground state.

We present a perturbative model for crystal-field calculations in f-electron compounds, which keeps into account the mixing between states labelled by different total angular momentum J. We use this model to analyze the results of inelastic neutron scattering experiments on actinide dioxides accumulated over a number of years. By comparing our calculations with the published results of other experiments, we point out that a unified crystal-field picture for this series of compounds clearly emerges.

The magnetic properties of the 5f5 [tris-(tri-1-pyrazolylborato)–plutonium(III)] complex have been investigated by ac susceptibility measurements, showing it to be the first plutonium single-molecule magnet; its magnetic relaxation slows down with decreasing temperature through a thermally activated mechanism followed by a quantum tunnelling regime below 5 K.