Unstable intermediates. Part XLIX. Solvated electrons: electron spin resonance and optical absorption spectra of solutions of the alkali metals in hexamethylphosphoramide

Abstract

Dilute, blue solutions (<10^–3M) of alkali metals in hexamethylphosphoramide are characterised by an intense, asymmetric absorption band in the 4000 cm.^–1 region and a single e.s.r. absorption at g= 2·0021 with a width (ΔH_ms) of 0·035 gauss. More concentrated solutions (ca. 10^–1M) have, in addition, an intense, broad band at 13,800 cm.^–1, which is still present when the solutions have largely decomposed. Attempts to make the radical anion (Me₂N)₃PO^– by standard procedures were unsuccessful. It is concluded that the blue solutions resemble metal–ammonia solutions, and the optical and e.s.r. absorption bands are assigned to solvated electrons.