Cation-electron interactions in metal solutions - from solvated electrons to alkali metal anions

Abstract

Abstract The solvent has a pronounced effect on the nature of species formed by solvated electrons and alkali metal cations. Neutral species form, which can be described as solvent-shared and contact ion-pairs. However, short-range “core” repulsions characteristic of normal contact pairs are absent so that a continuum of states with varying atomic character exists depending upon the solvent, the metal, and the temperature. In addition to cation-electron interactions, electron-electron interactions occur which stabilize singlet ground states. The cation can play a major role in this process, retaining its own solvation in a good donor solvent such as ammonia or forming a genuine alkali metal anion with two electrons in the outer s orbital in poorer donor solvents. Intermediate states such as contact triple-ions may also form but there is no direct evidence for such species.