ChemInform Abstract: CONDUCTION‐ AND LOCALIZED‐ELECTRON SPIN RESONANCE IN THE LITHIUM‐METHYLAMINE SYSTEM: INFERENCES FOR THE EXISTENCE OF THE METALLIC COMPOUND TETRAMETHYLAMINELITHIUM(ZERO), LI(CH3NH2)4

Abstract

Electron spin resonance (ESR) studies of fluid and frozen solutions of lithium in anhydrous methylamine are reported. The composition and temperature dependence of the ESR properties (electron spin relaxation times, electronic ge factor) are indicative of metallic compound formation in the lithium–methylamine system at low temperatures. Marked changes in both the electron spin relaxation properties and the ESR line shapes in the temperature interval 156–158 K are consistent with those expected for a metallic system moving through the melting point. Electron spin relaxation characteristics of the corresponding metal–ammonia compounds Li(NH3)4 and Ca(NH3)6 have been adequately interpreted in terms of a nearly free‐electron (NFE) picture for these low electron density materials. In contrast, electronic properties of the compound tetramethylaminelithium(zero), although nominally metallic (σ∼400 Ω−1 cm−1 for a 22 mole% metal fluid solution), cannot be described in the context of a NFE material. In particular, ...