Cerocene and Lanthanocene Chalcogenides: Synthesis, Structure, and Luminescence

Area of Science:

• Organometallic Chemistry
• Lanthanide Chemistry
• Coordination Chemistry

Background:

• Lanthanide chalcogenides are important materials with diverse applications.
• Synthesis of novel lanthanide complexes with chalcogen elements remains an active area of research.
• Understanding the reactivity of lanthanide alkyl complexes is crucial for developing new synthetic routes.

Purpose of the Study:

• To synthesize and characterize new lanthanide chalcogenide complexes.
• To investigate the reactivity of lanthanide alkyl complexes with elemental selenium and tellurium.
• To explore the luminescence properties of the synthesized cerium(III) and lanthanum(III) complexes.

Main Methods:

• Reaction of lanthanide alkyl complexes with elemental selenium or tellurium in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN).
• Characterization using various spectroscopic methods (e.g., NMR, IR).
• Solid-state structure determination via single-crystal X-ray diffraction.
• Luminescence spectroscopy for optical property analysis.

Main Results:

• Successful synthesis of six new lanthanide chalcogenide complexes: {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln}₂(μ-η²:η²-Te₂) (Ln = Ce, La), {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(THF)}₂(μ-Se) (Ln = Ce, La), and {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(THF)}₂(μ-Te) (Ln = Ce, La).
• Identification of lanthanide (cyclooctane-1,5-diyl)dihydroborate complexes as potential intermediates in the synthesis.
• Cerium(III) complexes (3 and 5) displayed distinct luminescence compared to their lanthanum(III) counterparts (4 and 6).
• Complex 5 exhibited unexpected red emission in solution, sensitive to excitation wavelength.

Conclusions:

• The study successfully synthesized novel lanthanide chalcogenide complexes, expanding the library of known organometallic lanthanide compounds.
• The findings suggest a plausible reaction mechanism involving lanthanide hydrides as key intermediates.
• The luminescence properties of Ce(III) complexes highlight their potential for optical applications, with complex 5 showing unique solution-state emission behavior.