Strong Bases Design: Predicted Limits of Basicity.

Area of Science:

• Organic Chemistry
• Computational Chemistry
• Physical Chemistry

Background:

• Brønsted superbases are crucial for activating C-H bonds in organic synthesis.
• Substituted aminophosphazenes represent the strongest neutral bases to date, developed in the late 1980s.
• Ongoing research aims to synthesize even stronger neutral bases for enhanced chemical reactivity.

Purpose of the Study:

• To investigate the theoretical reasons behind the instability of highly basic compounds.
• To establish theoretical limits for basicity in both solution and gas phases.
• To propose a novel, stable superbase synthesizable under ambient conditions.

Main Methods:

• High-level quantum-chemical calculations were employed to analyze molecular stability and basicity.
• Theoretical models were used to predict basicity limits in different environments.
• Hexamethylphosphoramide was identified as a suitable ionizing solvent for superbases.

Main Results:

• The study elucidates the factors contributing to the instability of extremely basic molecules.
• Theoretical basicity limits were determined for gas-phase and solution-phase conditions.
• A promising candidate for a record-breaking, stable superbase at ambient conditions was identified.

Conclusions:

• Understanding instability is key to designing stable, potent superbases.
• The proposed superbase offers potential for significant advancements in C-H bond activation.
• Hexamethylphosphoramide is a viable solvent for working with these powerful bases.