Structural and Spectroscopic Characterizations of Amide-AlCl3-Based Ionic Liquid Analogues

Area of Science:

• Materials Science
• Inorganic Chemistry
• Physical Chemistry

Background:

• Ionic liquids (ILs) offer tunable properties for diverse applications.
• Understanding the coordination chemistry of amide-AlCl3 systems is crucial for designing new ILs.
• The role of substituents on amide ligands impacts IL structure and reactivity.

Purpose of the Study:

• To synthesize and characterize novel amide-AlCl3 ionic liquid analogues.
• To investigate the influence of methyl group substitution on amide coordination and AlCl3 splitting.
• To correlate steric and inductive effects with the formation of ionic species.

Main Methods:

• One-step synthesis of amide-AlCl3 IL analogues using various amide donors.
• Spectroscopic analysis including (27)Al NMR, Raman, in situ IR, and UV-vis.
• Investigation of coordination modes (monodentate vs. bidentate) and asymmetric AlCl3 splitting.

Main Results:

• Bidentate coordination (O and N atoms) was dominant in N-methylacetamide-AlCl3 and N,N-dimethylacetamide-AlCl3 analogues due to inductive effects.
• Acetamide-AlCl3 analogue showed predominantly monodentate coordination (O atom).
• Bidentate coordination promoted asymmetric AlCl3 splitting more effectively than monodentate coordination.
• Ionic species percentages followed the order: N-methylacetamide > N,N-dimethylacetamide > acetamide, influenced by steric and inductive effects.

Conclusions:

• Methyl group substitution on the amide nitrogen significantly impacts coordination behavior and AlCl3 splitting in IL analogues.
• Bidentate coordination enhances AlCl3 asymmetry and increases ionic species formation.
• The findings provide insights into the structure-property relationships of amide-AlCl3 ionic liquids.