The band maxima of transient optical absorption spectra observed by pulse radiolysis in ethylamine (EA)/tetrahydrofuran (THF) mixtures containing sodium tetraphenylboron are correlated with electron spin resonance (esr) hyperfine splitting constants obtained in potassium/EA/THF solutions. The data suggest that the optical spectra can be attributed to the same 'monomeric' species as observed by esr in alkali metal solutions.

Electron spin resonance spectra of solutions of p o t a s s i~~m in tetrahqdrofuran-ethylamine. tetrahydrofuran-diglyme, ethylamine-diglyme. and ethylamine-ethylenediamine mixtures are reported and compared with spectra obtained from the four pure solvents. Strong evidence for preferential solvation was observed in all mixtures, with the strength of solvation increasing in the order tetrahydrofuran < ethylamine < diglyme < ethylenediamine. Electron spin resonance spectra of mixtures containing ethylenediamine were used to investigate the nature of the single line spectrum obtained from solutions in ethylenediamine alone. It is concluded that this signal is an 'ammonia-like' time averaged spectrum arising from solvated electrons and ion-pairs. R. CATTERALL. J. S L A T E R~~ M. C. R. S~hlolus. Can. .I. Chem. 55. 1979Chem. 55. (1977 On rapporte des spectres rpe de solutions de potassium dans des melanges de tetrahydrofuranneithqlamine, tetrahydrofuranne-diglyme. ethylamine-diglyme et ethylamineithylenediamine et on les compare avec les spectres obtenus Lpartir-des quatre solvants purs. I1 y a de fortes indications que l'on obsel-ve Line sol\ratation preferentie!le dans tous les melanges alors que la force de solvatation augmente dans I'ordre tetrahydrof~~ranne < ethylamine diglyme < ethylenediamine. On a utilise les spectres rpe de melanges contenant de I'ethylenediamine pour et~idier la nature du spectre avec une seule ligne obtenu pour des solutions dans I'ethylenediamine seul. On en conclut que ce signal est un spectre moyenne dans le temps ressemblant Ll'ammoniac et qui derive d'electrons solvates et de paires d'ions.[Traduit par le journal]

The 14N hyperfine coupling in the anions of mononitrobenzene and mor p-dinitrobenzenes is sensitive to environment. In methanol or ethanol the coupling constants are large because hydrogen bonding strongly perturbs the structure. Addition of sodium or lithium salts results in the formation of ion-pairs with slightly enhanced 14N coupling. In contrast, tetra-n-butylammonium salts cause a gradual shift to smaller coupling constants. This is interpreted in terms of displacement of alcohol molecules by alkylammonium ions. In ethers, the 14N coupling constants for alkylammonium salts are far lower than those for alkali metal salts and there is a marked increase on going from caesium ions to lithium ions. However, the perturbation by alcohol solvent is much greater than that by lithium ions in ethereal solution. These results, together with results in mixed alcohol +ether solvents and various line-broadening phenomena, are discussed in terms of the nature of the ion-pairs involved.

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