Chloride-bridged, defect-dicubane {Ln4} core clusters: syntheses, crystal structures and magnetic properties

Designing Quantum Spaces of Higher Dimensionality from a Tetranuclear Erbium-Based Single-Molecule Magnet

The spin relaxation of an Er3+ tetranuclear single-molecule magnet, [Er(hdcCOT)I]4, (hdcCOT = hexahydrodicyclopentacyclooctatetraenide dianion), is modeled as a near-tetrahedral arrangement of Ising-type spins. Combining evidence from single-crystal X-ray diffraction, magnetometry, and computational techniques, the slow spin relaxation is interpreted as a consequence of symmetry restrictions imposed on quantum tunneling within the cluster core. The union of spin and spatial symmetries describe a ground state spin-spin coupled manifold wherein 16 eigenvectors generate the 3D quantum spin-space described by the vertices of a rhombic dodecahedron. Analysis of the experimental findings in this context reveals a correlation between the magnetic transitions and edges connecting cubic and octahedral subsets of the eigenspace convex hull. Additionally, the model is shown to map to a theoretically proposed quantum Cayley network, indicating an underexplored synergy between mathematical descriptions of molecular spin interactions and quantum computing configuration spaces.

Six-coordinated dinuclear lanthanide(III) amide complexes: investigation of magnetization relaxation dynamics and their electronic structures

A series of rare six-coordinated dinuclear Ln(III) complexes [Ln₂(μ-Cl)₂Cl₄Li₂(L)₂(THF)₆] were structurally characterized using a bulky amide ligand (L; Ln = Gd(1), Dy(2) and Y(3)). Detailed magnetic studies disclose that a weak antiferromagnetic coupling exists within 1 (-0.09 cm^-1) and 2 (-0.07 cm^-1; -2J Hamiltonian). Additionally, this study unveils the importance of the amide ligand at the coordination site of Dy(III), which manifests a slow relaxation of magnetization in the absence of an external magnetic field. This has been rationalized by detailed ab initio calculations as well as the electronic structure determination of 1 and 2.

Slow Magnetic Relaxation in Mono- and Bimetallic Lanthanide Tetraimido-Sulfate S(NtBu)4 2- Complexes

Lanthanide ions are particularly well-suited for the design of single-molecule magnets owing to their large unquenched orbital angular momentum and strong spin-orbit coupling that gives rise to high magnetic anisotropy. Such nanoscopic bar magnets can potentially revolutionize high-density information storage and processing technologies, if blocking temperatures can be increased substantially. Exploring non-classical ligand scaffolds with the aim to boost the barriers to spin-relaxation are prerequisite. Here, the synthesis, crystallographic and magnetic characterization of a series of each isomorphous mono- and dinuclear lanthanide (Ln=Gd, Tb, Dy, Ho, Er) complexes comprising tetraimido sulfate ligands are presented. The dinuclear Dy complex [{(thf)2 Li(NtBu)2 S(tBuN)2 DyCl2 }2  ⋅ ClLi(thf)2 ] (1c) shows true signatures of single-molecule magnet behavior in the absence of a dc field. In addition, the mononuclear Dy and Tb complexes [{(thf)2 Li(NtBu)2 S(tBuN)2 LnCl2 (thf)2 ] (2b,c) show slow magnetic relaxation under applied dc fields.

Single-Ion Anisotropy and Intramolecular Interactions in CeIII and NdIII Dimers

This article reports the syntheses, characterization, structural description, together with magnetic and spectroscopic properties of two isostructural molecular magnets based on the chiral ligand N,N'-bis((1,2-diphenyl-(pyridine-2-yl)methylene)-(R,R/S,S)-ethane-1,2-diamine), L1, of general formula [Ln2(RR-L1)2(Cl6)]·MeOH·1.5H2O, (Ln = Ce (1) or Nd (2)). Multifrequency electron paramagnetic resonance (EPR), cantilever torque magnetometry (CTM) measurements, and ab initio calculations allowed us to determine single-ion magnetic anisotropy and intramolecular magnetic interactions in both compounds, evidencing a more important role of the anisotropic exchange for the NdIII derivative. The comparison of experimental and theoretical data indicates that, in the case of largely rhombic lanthanide ions, ab initio calculations can fail in determining the orientation of the weakest components, while being reliable in determining their principal values. However, they remain of paramount importance to set the analysis of EPR and CTM on sound basis, thus obtaining a very precise picture of the magnetic interactions in these systems. Finally, the electronic structure of the two complexes, as obtained by this approach, is consistent with the absence of zero-field slow relaxation observed in ac susceptibility.

An unsymmetrical dinuclear scandium complex comprising salophen ligands [H2salophen = N,N'-bis-(salicyl-idene)-1,2-phenyl-enedi-amine]

Treatment of scandium nitrate tetra-hydrate with the tetra-dentate ligand H2salophen [N,N'-bis-(salicyl-idene)-1,2-phenyl-enedi-amine] afforded the yellow dinuclear complex Sc(NO3)2(μ-salophen)Sc(salophen)(EtOH) or [Sc2(C20H14N2O2)2(NO3)2(C2H6O)] (systematic name: (ethanol-κO)bis-(nitrato-κ2 O,O'){μ-2,2'-[1,2-phenyl-enebis(nitrilo-methanylyl-idene)]diphenolato-κ4 N,N',O,O':κ2 O,O'}{2,2'-[1,2-phenyl-enebis(nitrilo-methanylyl-idene)]diphenolato-κ4 O,N,N',O'}discandium). In this compound, one salophen ligand displays a bridging coordination via the two oxygen atoms, while the other salophen ligand is attached to only one Sc center. This arrangement is stabilized by a hydrogen-bonded EtOH co-ligand, and by π-π stacking inter-actions between the two salophen ligands.

A dichlorido-bridged dinuclear Dy(iii) single-molecule magnet with an effective energy barrier larger than 600 K

We report a dichlorido-bridged dinuclear dysprosium(iii) single-molecule magnet [Dy(Cy2N)2(μ-Cl)(THF)]2 which shows an effective energy barrier for magnetization reversal (Ueff) of ca. 623 K. This is by far the largest Ueff barrier for any chlorido-bridged lanthanide single-molecule magnet. We observe two relaxation processes with near-identical temperature dependencies, one of which disappears upon magnetic dilution. We suspect that these two processes are the isolated and coupled relaxation processes.

A Dy4 single-molecule magnet and its Gd(iii), Tb(iii), Ho(iii), and Er(iii) analogues encapsulated by an 8-hydroxyquinoline Schiff base derivative and β-diketonate coligand

We report five tetranuclear Ln^IIIcomplexes encapsulated by 5-(benzylidene)amino-8-hydroxyquinoline and the β-diketonate coligand.

A salen-type Dy4 single-molecule magnet with an enhanced energy barrier and its analogues

A discrete hexadentate salen-type tetranuclear Dy complex with a unique {Ln₄O₈} core exhibits two slow magnetic relaxations with the highest energy barrier of 48.14 K among the reported tetranuclear salen-type dysprosium SMMs.

Double-malate bridging tri-lanthanoid cluster encapsulated arsenotungstates: syntheses, structures, luminescence and magnetic properties

Five members of a new family of POM-ligated double-malate bridging tri-lanthanoid clusters have been synthesized and characterized.