Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling

Area of Science:

• Coordination Chemistry
• Magnetochemistry
• Materials Science

Background:

• Lanthanide(III) ions are crucial in developing molecular magnetic materials.
• Nitroxyl radicals offer paramagnetic properties for magnetic interactions.
• Designing isomorphous complexes allows systematic studies of magnetic properties.

Purpose of the Study:

• To synthesize and characterize novel isomorphous mononuclear lanthanide(III) complexes with a tripodal oxazolidine nitroxyl radical.
• To investigate the magnetic properties, including magnetic coupling and single-molecule magnetic behavior.
• To establish structure-property relationships in these lanthanide-radical systems.

Main Methods:

• Synthesis of mononuclear complexes using lanthanide nitrates in acetonitrile.
• Structural characterization via X-ray crystallography.
• Magnetic property measurements including DC magnetometry and Electron Paramagnetic Resonance (EPR) spectroscopy.

Main Results:

• Isomorphous complexes of the type [LnRad(NO₃)₃] were obtained for Ln = Gd, Tb, Dy, Tm, Y.
• The coordination polyhedron is LnO₇N₂, resembling a tricapped trigonal prism.
• A record 23 cm^-1 antiferromagnetic coupling was observed for Gd-Rad.
• The terbium derivative demonstrated single-molecule magnetic behavior with an effective barrier of 57 cm^-1 at 0.1 T.

Conclusions:

• The synthesized complexes represent a new class of lanthanide-nitroxyl radical compounds.
• The strong antiferromagnetic coupling highlights the potential for designing advanced magnetic materials.
• The observed single-molecule magnetic behavior in the terbium complex opens avenues for molecular spintronics.