Cationic Group-IV pincer-type complexes for polymerization and hydroamination catalysis.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Polymer Science

Background:

• Unsymmetrical dianionic {N,C,N'} pincer ligands offer unique coordination environments.
• Zirconium (Zr) and Hafnium (Hf) complexes are known for catalytic applications.
• Metal-carbon bonds are crucial for stabilizing reactive metal centers.

Purpose of the Study:

• To synthesize and characterize neutral Zr(IV) and Hf(IV) dimethyl complexes with {N,C,N'} pincer ligands.
• To investigate the catalytic activity of these complexes in organic transformations and polymerization reactions.

Main Methods:

• Synthesis of neutral Zr(IV) and Hf(IV) bis-amido complexes.
• Treatment with AlMe3 to form Zr(IV) and Hf(IV) dimethyl complexes.
• In situ conversion to cationic species for catalytic studies.
• Catalysis of intramolecular hydroamination/cyclization and ethylene-1-octene copolymerization.

Main Results:

• Successfully prepared neutral Zr(IV) and Hf(IV) dimethyl complexes stabilized by {N,C,N'} pincer ligands.
• Demonstrated the formation of robust M-C bonds due to the ligand framework.
• Identified cationic derivatives as active catalysts for hydroamination/cyclization at room temperature.
• Showcased high-temperature catalytic activity in ethylene-1-octene copolymerizations.

Conclusions:

• The {N,C,N'} pincer ligand framework provides a unique balance of stability and reactivity in Zr(IV) and Hf(IV) complexes.
• These complexes, particularly their cationic forms, are effective catalysts for key organic transformations and olefin polymerizations.