Abstract
Ion association in aqueous solutions of scandium sulfate has been investigated at 25 degrees C and at concentrations from 0.01 to 0.8 M by broadband dielectric spectroscopy over the frequency range 0.2 <= nu/GHz <= 89. Detailed analysis of the spectra reveals the presence of both inner- and outer-sphere 1:1 [ScSO4](+)(aq) complexes, similar to solutions of other high-valent metal sulfates. ...
Abstract
Ion association in aqueous solutions of scandium sulfate has been investigated at 25 degrees C and at concentrations from 0.01 to 0.8 M by broadband dielectric spectroscopy over the frequency range 0.2 <= nu/GHz <= 89. Detailed analysis of the spectra reveals the presence of both inner- and outer-sphere 1:1 [ScSO4](+)(aq) complexes, similar to solutions of other high-valent metal sulfates. Outer-outer-sphere 1:1 complexes are probably also formed, but their contribution is swamped by the presence of higher-order inner-sphere complexes. The latter predominate in the more concentrated solutions, causing major changes to the low-frequency end of the spectrum. The data, while not definitive, are consistent with fac-[Sc(SO4)(3)(OH2)(3)](3-) as the major species present. The speciation is strikingly different from that recently reported for aluminum sulfate solutions and indicates that the often-postulated similarity between the aqueous chemistry of Al(III) and Sc(III) has to be treated with caution.
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