Proton magnetic resonance hydration study of scandium, yttrium, and thorium perchlorate in water-acetone mixtures

A proton magnetic resonance coordination number and ion-pairing study of GaCl3, GaBr3, GaI3, Ga(NO3)3and Ga(ClO4)3in acetone-water mixtures

“…Several examples of this type of application have been provided by the authors in coordination number determinations of ions in water and aqueous solvent Downloaded by [Tulane University] at 16:57 21 June 2016 mixtures [11][12][13][14][15][16][17][18][19][20]. At low temperatures, the normally rapid proton exchange is slowed sufficiently, permitting the observation of separate resonance signals for bulk water and water molecules in the Ga 3+ solvation shell.…”

“…hydration studies of Th +4 in water-acetone mixures in these laboratories [18,20]. It was found that the Th 4+ hydration number decreased from a value of 10 in C104-solutions with little, if any, ion-pairing [20], to a value of about 3 in NO3-solutions [18]. The trend among the halides could be anticipated from a consideration of surface charge densities, and relative basic strengths, properties which decrease in the order CI-> Br-> I-.…”

“…Recently we demonstrated that by cooling concentrated, pure aqueous solutions of many cations, or more dilute samples of these cations in aqueous solvent mixtures, proton exchange could be slowed sufficiently to permit the direct observation of signals for the protons of bulk water and water in the ion solvation shell [11][12][13][14][15][16][17][18][19][20]. Like the oxygen-17 method, this technique provides an accurate and quantitative measure of an ion coordination number, but it requires only readily available Downloaded by [Tulane University] at 16:57 21 June 2016 instrumentation, no sample enrichment, and it is much more versatile.…”

Raman Spectroscopic Studies of Scandium(III) Hydration in Aqueous Solution - about the First Hydration Sphere of Sc(III) in Solution

“…The results of a recent crystal structure of scandium(III) trifluoromethan enneahydrate [Sc(OH 2 ) 9 (CF 3 SO 3 ) 3 ] [7] reveal that Sc 3ϩ is surrounded by 9 water molecules (tricaped trigonal prism) with six short Sc 3ϩ -O bonds (2.171 Å ) and three longer bonds (2.47 Å ). 1-H-NMR measurements [8] on Sc(III)-perchlorate and -nitrate in water-acetone mixtures were carried out, but the coordination number of the first hydration sphere could not be detected because of the rapid proton exchange between bulk and water in the first coordination sphere, even at Ϫ100°C for perchlorate solutions. In nitrate solutions unusually low hydration values of 3.9 to 5.1 were detected, which clearly indicated that hydrolysis and nitrato complex formation were important in this solution.…”

Actinides in Solution: Complexation and Kinetics

“…From NMR peak areas, an estimate of the primary hydration number of Th(IV) in an aqueous acetone solution of Th(ClO 4 ) 4 at À100 C indicated a hydration number of 9 (Butler and Symons, 1969;Fratiello et al, 1970a) whereas an indirect, NMR line width method gave N H 2 O ¼ 10 (Swift and Sayre, 1966). However, the direct and accurate method of solution X-ray diffraction gave N H 2 O ¼ (8:0 AE 0:5) for acidic, 1À2 M Th(ClO 4 ) 4 and ThCl 4 solutions (Johansson et al, 1991).…”