title: Scandium sulfate complexation in aqueous solution by dielectric relaxation spectroscopy.
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 <or= nu/GHz <or= 89. Detailed analysis of the spectra reveals the presence of both inner- and outer-sphere 1:1 [ScSO 4] (+)(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(SO 4) 3(OH 2) 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.
authors.affiliation: Chemistry Department, Murdoch University, Murdoch, WA 6150, Australia. simon@schroedle.de
authors.forename: Simon
authors.initials: S
authors.lastname: Schrödle
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wachter
authors.forename: Richard
authors.initials: R
authors.lastname: Buchner
authors.forename: Glenn
authors.initials: G
authors.lastname: Hefter