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

Abstract

. 55,3356 (1977). Pulse radiolysis of tetrahydrofuran (THF), dimethoxyethane (DME), diglyme (DG), and triglyme (TG), results in the formation of solvated electrons, e,-, with optical band maxima h, , . 2 1840 nm. In the presence of alkali metal salts transient optical bands are observed with h,,. at -900 and 2 1600 nm. The latter bands are assigned to the formation of 'monomeric' species of stoichiometry M considered to be 'tight' and 'loose' ion-pairs, respectively. The proportion of 'loose' ion-pairs increases with decreasing temperature and increasing coordination of the solvent in the order THF << DME < DG < TG. These results demonstrate a good correlation with established electron spin resonance data in alkali metal solutions and substantiate the coexistence of at least two 'monomeric' species in DME and the glymes. THF << DME < DG < TG. Ces rksultats dkmontrent une bonne corrklation avec les donnkes ktablies par resonance de spin Clectronique en solutions de mktaux alkalins et justifient la coexistence d'au moins deux esptces "monorntres" dans le DME et les glymes.[Traduit par le journal]

Flash photolysis of alkali metal anions in tetrahydrofuran and dimethoxyethane

“…The primary photolysis step metal solutions containing sodium/potassium, sois considered to be reaction [ l ] involving the forma-diumlrubidium, and sodium/cesium. The results tion of solvated electrons, e,-, and a species of clearly substantiate the conclusions reached earlier stoichiometry M, best regarded as a n ion-pair by pulse radiolysis (4,6). However, because of Na+ contamination and, what been given elsewhere (7).…”

“…As mentioned earlier, reactions [4] and [5] produce M -also on a g ps time scale. The slow rate determining step for the 2 regeneration of Na-is considered to be reaction [13].…”

“…The analyzing light was filtered at the (DME) requires reinterpretation. Furthermore, a source with a Corning glass filter 112-62 and at the monomore recent study (4) has indicated a basic incon-chromator with either a 7-56 or a 1400 nm "cut-on" interference filter at the appropriate wavelengths. Quartz flow syssistenc~ in the spectra attributed to the tems containing 2 cm x 1 cm diameter reaction were (Na+, e3-1, as generated by flash ~h o t o l~s i s (315 and otherwise identical to those described ~reviouslv (8.…”

Searching for solvent cavities via electron photodetachment: The ultrafast charge-transfer-to-solvent dynamics of sodide in a series of ether solvents

“…blueshifted to near 1600 nm. 74,75 Thus, the interaction between sodium cations and electrons varies significantly across our series of ethers: in liquid THF, only the TCP is observed at equilibrium at room temperature, 76 whereas both the TCP and LCP appear in equilibrium with each other in DME and DG, and neither is observed at equilibrium in DEE.…”

“…We also note that pulse radiolysis experiments suggest that the interactions between sodium cations and electrons in both DME and DG are more complex than what is observed in THF. 74,75 In both DME and DG, the room-temperature solvated neutral sodium species exists in two forms as an equilibrium between a TCP, which absorbs near 900 nm as in THF, and a loose-contact pair ͑LCP͒, which has an absorption spectrum similar in shape to that of the solvated electron but with its spectral maximum TABLE I. Bulk properties of the ether solvents used in this study: n is the index of refraction, is the viscosity, ⑀ / ⑀ 0 is the static dielectric constant, and E T N is a measure of the solvatochromatic shift in the absorption spectrum of penta-tert-butyl pyridinium N-phenolate betaine in solution ͑see text͒.…”