ELECTRIDES AND ALKALIDES - COMPARISON WITH METAL SOLUTIONS

Abstract
The similarities between species in ammonia, amine and ether solutions of the alkali metals and in crystalline alkalides and electrides is striking. In solution we can identify the species M⁺_solv, e^-_solv, M^-, M⁺e^-, "e₂⁼'", and at high concentrations, e^-_conduction. In alkalides, electrides and mixed systems, species analogous to each of these can be found, in addition to alkali metal anion dimers, M⁼_solv, and chains, (M^n-)_n. Since the last Colloque Weyl we have determined the crystal structures and properties of 30 alkalides and 4 electrides. Correlation of structures and properties can now be made and will be discussed. A potentially rich area of investigation is the solution and liquid-state chemistry of alkalides and electrides. It is likely that the compound Li(CH₃NH₂)₄, studied by Sienko and others some time ago in both the liquid (metallic) state and the solid (semiconductor?) state, is an electride. Analogous alkalides, such as Li⁺(H₂NCH₂CH₂NH₂)₂Na^-, Li⁺(CH₃NH₂)₄Na^-, Li⁺(C₂H₅NH₂)₄Na^- can be prepared and it appears that other alkali metal anions can be used instead of Na^-. The solubility and stability of alkalides and electrides dissolved in dimethyl ether suggest that these would be excellent systems for the study of the properties of alkali metal solutions.