Calcium complexes containing oxalamidinate ligands as catalysts for ε-caprolactone polymerization

Area of Science:

• Organometallic Chemistry
• Polymer Chemistry
• Catalysis

Background:

• Oxalamidinate ligands offer versatile coordination possibilities.
• Calcium complexes are increasingly explored as catalysts in organic synthesis.
• Ring-opening polymerization (ROP) is a key method for producing biodegradable polymers.

Purpose of the Study:

• To synthesize novel calcium oxalamidinate complexes.
• To investigate the catalytic performance of these complexes in the ring-opening polymerization of ε-caprolactone.
• To characterize the structure and properties of the synthesized complexes.

Main Methods:

• Synthesis of oxalamidinate ligand precursors.
• Reaction of precursors with calcium bis(trimethylsilyl)amide to form calcium complexes.
• Characterization of complexes using X-ray diffraction.
• Evaluation of catalytic activity in ε-caprolactone polymerization.

Main Results:

• A series of five novel calcium oxalamidinate complexes (6-10) were successfully synthesized.
• The molecular structure of complex 7 was confirmed by single crystal X-ray diffraction.
• Complex 8 showed excellent catalytic activity for the ring-opening polymerization of ε-caprolactone.
• The polymerization using complex 8 resulted in controlled molecular weights and narrow polydispersities.

Conclusions:

• Novel calcium oxalamidinate complexes can be effectively synthesized.
• These complexes hold potential as catalysts for controlled polymerization reactions.
• Complex 8 is a highly effective catalyst for the ring-opening polymerization of ε-caprolactone, offering control over polymer properties.