Superalkali-Alkalide Interactions and Ion Pairing in Low-Polarity Solvents

The nature of anionic alkali metals in solution is traditionally thought to be gaslike and unperturbed. In contrast to this noninteracting picture, we present experimental and computational data herein that support ion pairing in alkalide solutions. Concentration dependent ionic conductivity, dielectric spectroscopy, and neutron scattering results are consistent with the presence of superalkali-alkalide ion pairs in solution, whose stability and properties have been further investigated by DFT calculations. Our temperature dependent alkali metal NMR measurements reveal that the dynamics of the alkalide species is both reversible and thermally activated suggesting a complicated exchange process for the ion paired species. The results of this study go beyond a picture of alkalides being a gaslike anion in solution and highlight the significance of the interaction of the alkalide with its complex countercation (superalkali).

Automated summary

The study presents experimental and computational data supporting ion pairing in alkalide solutions, and reveals the presence of superalkali-alkalide ion pairs. Temperature-dependent NMR measurements show that the dynamics of alkalide species is reversible and thermally activated, indicating a complex exchange process for ion-paired species. The results go beyond the traditional gaslike anion picture, emphasizing the significance of interactions between alkalide and its complex countercation (superalkali).