Alkaline earth metallocenes coordinated with ester pendants: synthesis, structural characterization, and application...

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Synthetic Chemistry

Background:

• Cyclopentadiene derivatives are versatile ligands in organometallic chemistry.
• Heavier alkaline earth metals (Ca, Sr, Ba) offer unique electronic and steric properties for metallocene complexes.

Purpose of the Study:

• To synthesize novel heavier alkaline earth metallocenes with ester functionalities.
• To explore the structural characteristics of these new metallocenes.
• To investigate their utility in generating transition metal metallocenes.

Main Methods:

• One-pot synthesis involving 1,4-dilithio-1,3-butadienes, carbon monoxide, and acid chlorides.
• Deprotonation of ester-substituted cyclopentadienes using heavier alkaline earth bis(amide) bases.
• Single-crystal X-ray diffraction for structural elucidation.
• Metathesis reactions for transition metal metallocene synthesis.

Main Results:

• Efficient synthesis of various ester-substituted cyclopentadiene derivatives.
• Generation of new heavier alkaline earth metallocenes (Ca, Sr, Ba) in good to excellent yields.
• Structural characterization revealing intramolecularly coordinated ester pendants and multiply-substituted cyclopentadienyl ligands.
• High-yield conversion to transition metal metallocenes, including ferrocene derivatives and rhenium complexes.

Conclusions:

• A novel class of heavier alkaline earth metallocenes bearing ester pendants has been successfully synthesized and characterized.
• These metallocenes serve as valuable precursors for diverse transition metal complexes.
• The developed ligands and metallocenes hold potential for applications in coordination chemistry, organometallic chemistry, and organic synthesis.