Solutions of alkali metals in amines.

Electron spin resonance and electronic absorption spectra are described for solutions of potassium metal in ethylamine, propylamine, isopropylamine and n-butylamine. The electron spin resonance spectra consist of a quartet, attributed to "solvated metal atoms", Msolv, and a singlet arising from solvated electrons, esolv. The hyperfine splitting constant of the quartet is strongly dependent upon solvent and temperature. The electronic absorption spectra contain bands at about 15,000 cm.-1 and 12,000 cm.-1 It is concluded that the electronic absorption band at 15,000 cm.-1 does not arise from a transition of Msolv. An equilibrium is shown to exist between solvated atoms and electrons and its dependence upon solvent, temperature and metal concentration is explored. Concentration-broadening of the central singlet is interpreted in terms of interactions with the diamagnetic species which account for the majority of the dissolved metal. The electron spin resonance absorption of the solvated sodium atom in ammonia-ethylamine mixtures is reported. The atomic characters of the other solvated alkali atoms are compared with that of sodium and the species responsible for the hyperfine splittings in lithium solutions. Hyperfine splittings from lithium solutions were assigned to four equivalent nitrogen nuclei. A model is proposed for Msolv in terms of an equilibrium between two species, one having a very small hyperfine coupling and the other having a coupling close to the atomic value. The species present in lithium solutions is thought to be best described as an ion-pair.