Non-ionic organosuperbases have attracted significant interest due to their practical applications in catalysis and synthesis, as well as for fundamental reasons. Numerous families of superbases have been investigated and proposed, although many of these remain virtually unexplored.
Ivo Leito, Ilmar Koppel and colleagues, University of Tartu, Estonia, used DFT computations to study five families of potentially extremely strong superbases with the goal of predicting their basicity limits and finding the most promising core structures for further development. After proposing and validating a simple model for the dependence of basicity on the molecular framework, the researchers were able to demonstrate that guanidino phosphorus carbenes display the highest basicity limit of the compounds considered.
The gas-phase basicities of these compounds are expected to reach 370 kcal mol−1, which exceeds the values for the strongest inorganic alkali metal oxides and the K3N superbase. Thus, guanidino phosphorus carbenes represent the strongest neutral bases ever reported.
- Basicity Limits of Neutral Organic Superbases,
Ivo Leito, Ilmar A. Koppel, Ivar Koppel, Karl Kaupmees, Sofja Tshepelevitsh, Jaan Saame,
Angew. Chem. Int. Ed. 2015.
Guanidino phosphorus carbenes were reported to be the most basic neutral bases to date (gas-phase basicity: ca. 372 kcal mol−1), according to a DFT computational study of non-ionic organosuperbases.