Reactivity studies on lanthanum and cerium hydrido metallocenes

Area of Science:

• Organometallic Chemistry
• Lanthanide Chemistry
• Boron Chemistry

Background:

• Lanthanide alkyl complexes are versatile precursors in organometallic synthesis.
• The reactivity of lanthanum and cerium complexes with unsaturated organic molecules is of significant interest.
• Understanding the role of in situ generated hydride species is crucial for exploring new reaction pathways.

Purpose of the Study:

• To investigate the reaction of lanthanum and cerium alkyl complexes with 9-borabicyclo[3.3.1]nonane (9-BBN).
• To explore the reactivity of in situ generated lanthanum and cerium hydride complexes.
• To synthesize and characterize novel lanthanide complexes derived from these reactions.

Main Methods:

• Reaction of lanthanide alkyl complexes with 9-BBN in THF.
• Subsequent reactions of generated hydride species with cyclohexene oxide, Me3SiCl, phenazine, and white phosphorus.
• Characterization of new compounds using spectroscopic methods (NMR, IR) and single-crystal X-ray diffraction.

Main Results:

• Formation of lanthanum and cerium boroxide complexes ([η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(μ-OBC₈H₁₄)(THF)).
• Evidence for in situ generation of lanthanum and cerium hydride species, leading to ring-opened products with cyclohexene oxide.
• Synthesis of lanthanide chloride complexes ([η⁵-1,3-(Me₃C)₂C₅H₃]₂LnCl) and novel complexes with reduced phenazine and white phosphorus.

Conclusions:

• Lanthanum and cerium alkyl complexes react with 9-BBN to yield boroxide and hydride intermediates.
• The in situ generated lanthanide hydrides exhibit significant reactivity towards unsaturated substrates.
• Novel lanthanide complexes with phenazine and phosphorus ligands have been successfully synthesized and structurally characterized.