ELECTRON-SPIN RESONANCE STUDIES OF ION-PAIR FORMATION IN SOLUTIONS OF FREMY SALT

It is shown that Fremy's salt ((KSO3)2NO) is ion paired under a variety of experimental conditions. When dissolved in dioxane-water solutions in the presence of CsClO4, two superimposed spectra are observed. One spectrum is that normally observed. The other has an additional splitting by a single cesium ion. An estimate of the dissociation constant has been made. Solutions of (KSO3)2NO when in the presence of such salts as RbCl and CsCl show g value shifts which are interpreted in terms of the formation of ion pairs with the added alkali metal ions. Analysis of the shifts yields estimates of the dissociation constants of 1.7(±0.4) and 1.4(±0.4) for the RbCl and CsCl salts, respectively, for a single dissociation/association process. Finally, the ESR line shapes for dilute solutions of (KSO3)2NO as a function of added alkali metal ions have been studied. It is shown that in previous work some of the reported distortion was the result of magnetic field modulation at too large a frequency. However, when lower frequencies are used there still remains a small distortion which can be interpreted in terms of a small unresolved metal hfs in the range of 5-20 mG depending upon the salt. © 1979 American Chemical Society.