Isolable Lanthanide Metal Complexes of a Phosphorus-Centered Radical

Area of Science:

• Organometallic Chemistry
• Lanthanide Chemistry
• Main-Group Element Chemistry

Background:

• Phosphaalkenes are versatile building blocks in inorganic and organometallic chemistry.
• Lanthanide complexes are of interest due to their unique electronic and magnetic properties.

Purpose of the Study:

• To synthesize and characterize novel lanthanide complexes incorporating a phosphaalkene-derived radical anion.
• To investigate the magnetic properties and electronic structure of these new compounds.

Main Methods:

• Reaction of a diazafluorenylidene-substituted phosphaalkene with lanthanide precursors.
• Reduction using potassium graphite (KC8).
• Characterization by single-crystal X-ray diffraction, UV/vis spectroscopy, and superconducting quantum interference device (SQUID) measurements.

Main Results:

• Synthesis of three new lanthanide complexes: Cp*2Dy(N,N'-1), Cp*2Tb(N,N'-1), and Cp*2Gd(N,N'-1).
• Confirmation of the phosphaalkene moiety in the radical-anion state within the complexes.
• Observation of weak antiferromagnetic interactions between the phosphorus-radical centers and lanthanide ions.
• Identification of slow magnetic relaxation behavior in the dysprosium complex (2).

Conclusions:

• The study presents the first lanthanide metal complexes featuring a heavy main-group element-based radical.
• The synthesized complexes offer insights into the electronic and magnetic interplay between lanthanides and radical species.
• The observed magnetic properties, including slow magnetic relaxation, highlight the potential of these compounds in molecular magnetism.