A Trinuclear Radical-Bridged Lanthanide Single-Molecule Magnet

Area of Science:

• Coordination Chemistry
• Materials Science
• Magnetochemistry

Background:

• Lanthanide complexes are of interest for their unique magnetic properties.
• Organic radical ligands can mediate magnetic coupling between metal centers.
• Developing molecule-based magnets requires understanding magnetic interactions and relaxation dynamics.

Purpose of the Study:

• To synthesize and characterize triangular lanthanide complexes bridged by a hexaazatrinaphthylene (HAN) radical ligand.
• To investigate the magnetic coupling between lanthanide ions mediated by the HAN ligand.
• To explore the magnetic relaxation properties and potential for single-molecule magnet behavior in the dysprosium congener.

Main Methods:

• Synthesis of Cp*₆ Ln₃ (μ₃ -HAN) complexes under strongly reducing conditions.
• Magnetic susceptibility measurements (ac and dc) to probe magnetic coupling and relaxation.
• Magnetic hysteresis measurements to assess remnant magnetization and field-dependent behavior.

Main Results:

• Successful assembly of triangular lanthanide complexes Cp*₆ Ln₃ (μ₃ -HAN).
• Evidence of effective magnetic coupling between all three Ln^III centers through the HAN^3-. radical ligand.
• The Dy^III complex exhibits slow magnetic relaxation (U_eff =51 cm^-1) and open hysteresis loops up to 3.5 K.

Conclusions:

• The hexaazatrinaphthylene radical ligand effectively mediates magnetic coupling in triangular lanthanide assemblies.
• The dysprosium complex demonstrates promising properties for molecule-based magnetism, including slow magnetic relaxation and significant remnant magnetization.
• These findings contribute to the design of new magnetic materials based on lanthanide-radical interactions.