Quantitatively analyzing metathesis catalyst activity and structural features in silica-supported tungsten...

Area of Science:

• Organometallic Chemistry
• Catalysis
• Materials Science

Background:

• Development of well-defined heterogeneous catalysts is crucial for industrial applications.
• Silica-supported tungsten complexes offer tunable properties for olefin metathesis.
• Understanding structure-activity relationships is key to optimizing catalyst performance.

Purpose of the Study:

• To synthesize and characterize a series of silica-supported tungsten metathesis catalysts.
• To evaluate catalyst activity in the self-metathesis of cis-4-nonene.
• To establish quantitative structure-activity relationships for predicting catalyst performance.

Main Methods:

• Synthesis of silica-supported tungsten catalysts by grafting pre-formed complexes onto dehydroxylated silica.
• Evaluation of catalyst activity using turnover frequency (TOF) in cis-4-nonene self-metathesis.
• Application of multivariate linear regression analysis to correlate ligand properties with activity.

Main Results:

• A series of well-defined silica-supported tungsten catalysts with varying imido (NAr) and ancillary (X) ligands were prepared.
• Catalyst activity (TOF) was quantitatively predicted using steric (Sterimol B5) and electronic (NBO charge, IR intensity, pKa) parameters of the ligands.
• High activity was achieved by combining imido and ancillary ligands with opposite electronic characteristics.

Conclusions:

• Quantitative structure-activity relationships were established for silica-supported tungsten metathesis catalysts.
• Catalyst performance can be predicted based on simple steric and electronic ligand parameters.
• This work provides a foundation for the rational design of highly active heterogeneous metathesis catalysts.