Unstable intermediates. Part CIV. Electron spin resonance studies of solutions of lithium in ethylamine–diglyme mixtures

Abstract

Solutions of lithium in ethylamine are characterised by two e.s.r. features, one, comprising nine hyperfine lines, assigned to coupling with four equivalent nitrogen nuclei, and another, a single narrow line, assigned to solvated electrons. Although no lithium hyperfine coupling was detected, the former unit is thought to be an electron associated with the ion Li(EtNH₂)₄⁺. Addition of diglyme to such solutions gave an increase in the ¹⁴N hyperfine coupling, but no change in the number of hyperfine lines in the concentration range for which the solutions were sufficiently stable for measurement (⩽0·56 mol fraction diglyme). In contrast with pure ethylamine solutions, the ¹⁴N hyperfine coupling from the diglyme solutions increased on warming. On cooling, clear blue glasses were formed, and the two e.s.r. signals merged into a single broad line with widths between points of maximum slope in the range 14–24 G. This is assigned to the solvated electrons, the widths being a measure of the overall hyperfine coupling to ¹H and ¹⁴N.

Exposure of ethylamine–diglyme glasses to ⁶⁰Co γ-rays gave blue solids which, on bleaching with visible light, lost single e.s.r. lines having widths in the range 15–20 G. These units appear to be very similar to those obtained on freezing the lithium solutions.