Stability Constants of Scandium Complexes. I. Monocarboxylate Complexes Species

Abstract

The stability constants of scandium complexes with some carboxylate ligands were determined potentiometrically at 25.0 and 40.0 °C and at an ionic strength of 0.10 with potassium nitrate as supporting electrolyte. The constants of the scandium complexes were appreciably greater than those of the corresponding lanthanoid complexes, as expected. The changes in free energy, enthalpy, and entropy for the formation of the scandium complexes were calculated from the stability constants at two temperatures.

Effects of citrate, mandelate and ph on the release of aluminium from aluminosilicates

“…22 Our estimate, log Kj = ca. 3.7 (mandelate complexes are about 50 times more stable than the corresponding acetate complexes), compares reasonably with log Kj = 2.91 for scandium(III)-mandelate 23 and log K, = 1.60 for yttrium(III)-mandelate. 24 Aluminosilicates were chosen to provide a range of coordination environments (four, five, or six oxygens) around the aluminium, and a range of resistance to attack by potentially complexing media (Table 1).…”

Scandium-44: Benefits of a Long-Lived PET Radionuclide Available from the 44Ti/44Sc Generator System

“…While appli-cation of only 1 mL 0.1 M diammonium oxalate gave the best 44 Sc recovery (95%), however labeling of DOTATOC with 44 Sc as eluted by 1 mL of 0.1 M diammonium oxalate and added to 4 mL HEPES buffer (pH = 4.0) containing the peptide failed. Further studies were focused on ammonium acetate solutions, despite the fact that the recovery of 44 Sc by 2 mL of the utilized mixture was slightly lower than with oxalates [20,21]. High recovery of 44 Sc (~90%) was obtained, when 3 mL of a 0.25 M ammonium acetate buffer acidified to pH = 4.0 by addition of acetic acid was used.…”

Revision and Analysis of the Formation Constants of Rare Earth Diketonates

“…The interaction between diketones and scandium observes in more acidic media (pH 3.0–3.6, glycine–HCl buffer) than for other REMs (5.0–5.4 acetate buffer). The value of the stability constant for the Sc 3+ –glycine complex (log K = 7.75) is several orders of magnitude higher than that for the Sc 3+ –acetate complex (log K = 3.48) . If in the system, Sc 3+ /phenyl–CF 3 exchanges glycine–HCl buffer to acetate, then the conditional constant changes only 0.2 logarithmic units (Table S3) although the difference should be over 3 orders of magnitude.…”

“…The value of the stability constant for the Sc 3+ −glycine complex (log K = 7.75 38 ) is several orders of magnitude higher than that for the Sc 3+ −acetate complex (log K = 3.48). 39 If in the system, Sc 3+ /phenyl−CF 3 exchanges glycine−HCl buffer to acetate, then the conditional constant changes only 0.2 logarithmic units (Table S3) although the difference should be over 3 orders of magnitude. Thus, these facts also demonstrate the low impact of side ions.…”