Acidity Quantification and Structure Analysis of Amide-AlCl₃ Liquid Coordination Complexes for C₄ Alkylation...

Area of Science:

• Coordination Chemistry
• Catalysis
• Materials Science

Background:

• Liquid coordination complexes (LCCs) formed from metal halides and donor molecules show catalytic promise.
• Amide-aluminum chloride (AlCl3) LCCs are explored for their catalytic properties.

Purpose of the Study:

• To synthesize and characterize amide-AlCl3 LCCs.
• To investigate the relationship between LCC structure, acidity, and catalytic performance in alkylation reactions.
• To establish a foundation for designing targeted acid catalysts.

Main Methods:

• Synthesis of six amide-AlCl3 LCCs.
• Characterization using NMR, Raman, and UV-visible spectroscopy.
• Acidity quantification via computational fluoride ion affinities (FIA) and experimental Gutmann-Beckett measurements.
• Evaluation in C5-C7 alkylation reactions.

Main Results:

• Spectroscopic analysis confirmed bidentate coordination and asymmetric splitting of Al2Cl6 into various ions.
• Computed FIA values correlated well with experimental acidity trends, validating the proposed LCC structures.
• High-acidity LCCs significantly increased yields in alkylation reactions.

Conclusions:

• The structure and acidity of amide-AlCl3 LCCs are tuneable by adjusting the ligand-to-AlCl3 ratio.
• Bidentate coordination facilitates asymmetric Al2Cl6 splitting, influencing catalytic activity.
• These LCCs show potential as versatile, sustainable acid catalysts for alkylation, advancing catalyst design.