Model for Metal Ammonia Solutions

Abstract

A model is proposed for dilute metal ammonia solutions in which the neutral species is a metal ion solvated by ammonia molecules, with the valence electron from the metal ion localized on the protons of these ammonia molecules. This species can dissociate in a manner similar to an ion pair, and the equilibrium constant for this dissociation as estimated agrees with the one derived from electrical conductivity data. Also, two neutral species can associate to form a dimer species, and the calculated energy of formation of this dimer is in satisfactory agreement with the binding energy derived from magnetic susceptibility data. This model is consistent with the large volume increase on mixing and with some aspects of the absorption spectrum.