Pulse Radiolytic Formation of Solvated Electrons, Ion-pairs, and Alkali Metal Anions in Tetrahydrofuran

Abstract

. Can. 9. Chem. 52.3259(1974). Pulse radiolysis of solutions of alkali metal cations in tetrahydrofuran (THFj demonstrates the formation of solvated electrons e,-, alkali metal cation -ion pairs (M', e,-), and alkali metal anions M -. This paper describes the spectra, extinction coefficients, and radiolytic yields of es-, iithium, sodium, potassium, and cesium species in TFIF. The reaction kinetics are colnplex but largely involve reactions A and B with the concomitant disappearance of all three species by reaction with radiolytically produced radicals. Rate constants and ion-pair dissociation constants for e,-and the sodium and potassium species are presented and compared with data established from studies of blue solutions of alkali metals dissolved in THF. e,-+ M + (M+, e,-)

Solvated electrons and the effect of coordination on the optical spectra of alkali metal cation – electron pairs in ethers

“…In this work all experiments were conducted using a 1.0 cm cell and 0.3 ps pulses of 2.25 MeV electrons. Solution preparation and purification of THF were as described previously (12). DME (Eastman) and the glymes (Matheson, Coleman and Bell, and Aldrich Chemicals) were purified by refluxing over calcium hydride in an inert atmosphere followed by fractional distillation.…”

“…This solution was then cooled and decanted, under vacuum, from the alloy and the ethers subsequently redistilled into the appropriate flow system. Sodium and potassium tetraphenylboron salts were used to give solutions of the alkali metal cations (12). Figure 1 shows the optical absorption spectra of e,-observed at 21°C immediately after the pulse in pure DME, DG, and TG.…”

“…The DG and DME spectra are successively displaced vertically by two units for clarity in presentation. (10,12).…”

“…In THF it is well established that [2] produces the 900 nm band with a second order rate constant k, = 7.9 x 10'' M-' s-' (10,12) Because of spectral overlap it is not possible to measure the corresponding rate constants in DG, DME, or TG. However, changes in spectra such as depicted in Figs.…”

“…Optical (3), electron spin resonance (esr) (4,5), conductivity (6), flash photolysis (7)(8)(9), and pulse radiolysis (10)(11)(12) techniques have now clearly established the contribution of solvated electrons, e,-, cation-electron aggregates (M', e,-), and alkali metal anions M-to the chemistry of such solutions.…”