Vanadyl calix[6]arene complexes: synthesis, structural studies and ethylene homo-(co-)polymerization capability

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Polymer Science

Background:

• Calixarenes are versatile macrocyclic hosts with tunable properties.
• Vanadium and lithium complexes are of interest in catalysis.

Purpose of the Study:

• To synthesize and characterize novel vanadium-lithium calixarene complexes.
• To investigate the catalytic activity of these complexes in olefin polymerization.

Main Methods:

• Reaction of p-tert-butylcalix[6]arene with lithium tert-butoxide and vanadium precursors.
• Isolation and structural characterization of resulting complexes using X-ray crystallography.
• Evaluation of catalytic performance in ethylene and co-polymerization reactions.

Main Results:

• Synthesis of four novel vanadium-lithium calixarene complexes (1-5) with diverse structures, including a 1D polymer.
• Complexes 1 and 5 were identified as effective pre-catalysts for ethylene polymerization.
• Successful co-polymerization of ethylene with propylene and 1-hexene was achieved.

Conclusions:

• The synthetic strategy allows for the controlled assembly of vanadium-lithium calixarene architectures.
• These complexes represent a promising new class of pre-catalysts for olefin polymerization.
• Structural variations influence catalytic activity and selectivity.