A multimetallic iron(ii)-lithium complex as a catalyst for ε-caprolactone polymerization.

Area of Science:

• Organometallic Chemistry
• Polymer Chemistry
• Materials Science

Background:

• Multimetallic complexes offer unique reactivity and structural diversity.
• Iron-based catalysts are of interest due to iron's abundance and low toxicity.
• Ring-opening polymerization (ROP) is a key method for synthesizing polyesters like polycaprolactone.

Purpose of the Study:

• To synthesize and characterize a novel multimetallic iron(II)-lithium complex.
• To investigate the catalytic activity of this complex in ring-opening polymerization.

Main Methods:

• Synthesis involved the reaction of a β-ketimine lithium salt with FeCl₂(THF)_1.5, LiN(SiMe₃)₂, and water.
• Characterization of the resulting complex, [(L^Me)₂Fe]₃Li₂O, was performed.
• The complex was tested as an initiator for the ring-opening polymerization of ε-caprolactone.

Main Results:

• A novel {Fe₃Li₂O} core structure was successfully synthesized and identified.
• The complex acted as a highly efficient single-component initiator for ε-caprolactone ROP.
• Achieved 98% monomer conversion in 100 minutes at room temperature with a narrow PDI of 1.28.

Conclusions:

• The synthesized iron(II)-lithium complex exhibits promising catalytic activity for polymer synthesis.
• This study demonstrates the potential of multimetallic complexes as efficient initiators in controlled polymerization.
• The {Fe₃Li₂O} core represents an interesting structural motif with catalytic applications.