Shielding in Mixed Solvent and Non-Aqueous Solution

Halide ion shieldings have been determined in the presence of several different paramagnetic ions [ 257, 285, 287, 288, 290, 292, 341, 378]. It was found most convenient to describe the analysis of the effect of unpaired electrons on the shielding in connection with the relaxation effects in Section 5.2. 

This may, according to the Kondo - Yamashita model, be understood in 

For the alkali ions, and especially the sodium ion, information on the shielding is available for many more solvents (see e.g. Refs. [380-382]). Correlations of the shifts with solvent properties such as Lewis basicity [380] and Gutmann donor number [381-383] have been tried. 

A thorough discussion of the problems arising has been made recently by Covington and co-workers in a series of papers [384-388]. Here also the thermodynamic aspects of preferential solvation are considered. 

In their first paper [384], Covington et al. consider the case where, firstly, the solvation number is the same for both solvents and, secondly, the intrinsic shielding of an ion-solvent complex varies linearly with the composition of the first solvation sheath. 

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