Spectra of Na-, K-, and e-solv in amines and ethers

Abstract

By using cyclic polyethers of the crown and cryptate classes to complex the alkali cations, alkali metals were dissolved in secondary amines and in straight and branched chain ethers. In the absence of the complexing polyether, the metals are insoluble in these solvents. Pronounced solubility enhancement occurred in primary mono-and diamines, tetrahydrofuran, and diethers in which the metals are only very slightly soluble without the complexing agent. The optical spectra of Na-, K~, and, in most cases, e",0iv were measured for solutions in ethylamine, diethylamine, di-ra-propylamine, 1,2-propanediamine, hexamethylphosphoric triamide, diethyl ether, diisopropyl ether, tetrahydrofuran, dimethoxyethane, and diglyme. In most cases the peak positions were measured as functions of temperature. For each of the three species the wave number of maximum absorbance decreased linearly with an increase in temperature. Linear correlations were found for the changes in the peak positions of e-»0iv, Na-, and Kwith solvent at a given temperature. The spectra of Naand Kobey the criterion for a charge transfer to solvent (ctts) transition that the position of the peak be a linear function of the temperature coefficient. However, no satisfactory correlation between the peak positions of Naand K~and solvent properties has been found. The spectrum of e-,0iT has now been determined by metal solution studies, as well as by flash photolysis and pulse radiolysis techniques, for the solvents ammonia, ethylenediamine, diethylamine, diethyl ether, tetrahydrofuran, dimethoxyethane, and diglyme. The agreement between the peak positions in all cases is good. However, in some cases the band is substantially broader in metal solutions than in those studied by radiolysis.

Flash photolysis of alkali metal anions in tetrahydrofuran and dimethoxyethane

“…The reported optical spectra (13)(14)(15)(16) show good agreement in the position of the band maxima but often significant differences in band width and intensity, particularly on the high energy side of the spectrum. Utilizing the most reliable data (free of Na' contamination) (15, 16) in comparison with our own initial spectra, the overall band envelope for each M -species was established by a Gaussian-Lorenztian (G-L) shape function analogous to the method used for e,- (17)(18)(19).…”

Ultrafast Charge-Transfer-to-Solvent Dynamics of Iodide in Tetrahydrofuran. 2. Photoinduced Electron Transfer to Counterions in Solution

“…5 In addition to these investigations of the I -CTTS behavior in polar, protic solvents, the ultrafast CTTS dynamics of sodium anions, or sodide (Na -), in weakly polar, aprotic solvents has been studied in experiments both by Schwartz and coworkers [10][11][12][13][14][15][16]22 and by Ruhman and co-workers. 20,21 In liquid tetrahydrofuran (THF), Na -has a CTTS band that peaks near 720 nm (blue solid curve, Figure 1c), 56 a spectral region that is conveniently accessed with modern Ti:Sapphire lasers. Figure 1d demonstrates that excitation of the Na -CTTS band produces e solv -(whose equilibrium spectrum in THF is shown as the red dashed curve in Figure 1c 57 ), but with an appearance time of ∼450 fs.…”

The effect of temperature on the optical spectra and the yields of solvated electrons and ion-pairs in amines

“…These observations are consistent with the blue shift being due to an interaction between e,-and where G(e,-),,, and G(e,-),p,, represent the yields of the solvated escaped and spur electrons, respectively; S is the concentration of the scavenger, and a is a parameter which represents the reactivity of electrons towards the solute relative to their recombination with geminate positive ions or radicals (29 ,-),,, -0.6 and G(e,-)spur 1.2-1.6 (13), [2] only fits the data reasonably well above M scavenger concentration. Since there is a competition between the homogeneous decay of (e,-),,, and the scavenging process, [2] can be modified (1 I , 12) to give…”