Lewis Superacidic Ionic Liquids with Tricoordinate Borenium Cations

Area of Science:

• * Inorganic Chemistry
• * Materials Science

Background:

• * Ionic liquids (ILs) are salts that are liquid at low temperatures.
• * Lewis acids are crucial catalysts in various chemical reactions.
• * Developing stronger Lewis acids is essential for advancing chemical synthesis.

Purpose of the Study:

• * To synthesize and characterize novel ionic liquids based on borenium cations.
• * To investigate the Lewis acidity of these new compounds.
• * To establish a new class of exceptionally strong Lewis acids.

Main Methods:

• * Synthesis of borenium cations, [BCl2 L](+).
• * Characterization of ionic liquids under solvent-free conditions.
• * Quantification of Lewis acidity using the Gutmann acceptor number (AN) and 31P NMR spectroscopy.

Main Results:

• * Successful synthesis of the first borenium-based ionic liquids.
• * These ionic liquids exhibit extremely high Lewis acidity.
• * Recorded Gutmann acceptor numbers reached up to AN = 182, with δ31P = 120 ppm.

Conclusions:

• * Borenium ionic liquids represent a new class of potent Lewis superacids.
• * The ionic liquid environment significantly enhances Lewis acidity.
• * These findings open new avenues for catalysis and materials science.