Estimate of the stability constants of trivalent actinide and lanthanide complexes with O-donor ligands in aqueous solutions

Mishustin, A. I.

doi:10.1134/s0036023610050141

Cited by 9 publications

(6 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, we should note that the logarithmic stabil ity constants calculated earlier by a similar method [7] for bidentate coordinated carbonate complexes of lan thanides and actinides lie within the limits from 6.5 to 8.0, thus being in good agreement with experimental data. Hence, all types of ion pairs can be formed in the case of carbonate complexes, and there are no CIPs in sulfate complexes.…”

Section: Mishustinsupporting

confidence: 68%

“…where α is the local anion polarizability taken to equal 1.5 Å 3 , р is the polarization contribution correction taken to be equal to 3 Å as in [7]. The value of λ was taken to equal 0.1 Å -2 .…”

Section: Mishustinmentioning

confidence: 99%

“…(8) In calculations, we used the geometrical parameter of the Lennard Jones potential σ and also the cova lence parameter β, which were determined earlier [7] for each of the considered cations from the data for isolated monohydrates in the gas phase, and these val ues were used unchangeable in the calculations for the other O donating ligands [7]. ε was taken to equal 0.1 kcal/mol.…”

Section: Mishustinmentioning

confidence: 99%

“…Close values of the radii of anions with the same charge must have led to close values of stability constants of their complexes (for example, from the viewpoint of Bjer rum's ion association theory, association constants must not differ by more than 10%). An "abnormally" high stability of carbonate complexes in comparison with that of sulfate complexes is also observed for the complexes of other metals [1].To clarify the reason for such a sharp difference between the stabilities of the carbonate and sulfate complexes of tervalent lanthanides and actinides, in this study we used an earlier developed method of the oretical calculations of stability constants [6,7]. The method is based on integrating the function of the ligand distribution density with respect to a cation, and the selection of integration limits allows either all types of ion pairs or only SSIPs to be taken into account in calculations.…”

mentioning

confidence: 99%

“…To clarify the reason for such a sharp difference between the stabilities of the carbonate and sulfate complexes of tervalent lanthanides and actinides, in this study we used an earlier developed method of the oretical calculations of stability constants [6,7]. The method is based on integrating the function of the ligand distribution density with respect to a cation, and the selection of integration limits allows either all types of ion pairs or only SSIPs to be taken into account in calculations.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Stability constants of tervalent actinide and lanthanide sulfate complexes in aqueous solutions

Mishustin

2012

Russ. J. Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

The determination of thermodynamic and struc tural characteristics of metal complexes in solutions is one of the most important problems of chemistry. Sul fate anions are incorporated into atmospheric aero sols, natural waters, and many minerals and ores. Metal sulfate complexes play an important part in nat ural and engineering processes. Despite the fact that the kinetics and equilibrium of formation of metal sul fate complexes have been studied for many years by different experimental and kinetic methods, their thermodynamic properties (stability constants, etc.) are known only for a restricted number of metals [1]. Owing to experimental difficulties in the operation with radioactive compounds, data for actinides are very scanty. There is no common view on the type of complex formed (inner sphere or outer sphere) in the literature. According to [2], the formation of cation complexes in a solution is considered as a multistage process: first, ions approach each other and form sol vent separated ion pairs (SSIP), some of which may form a contact ion pair (CIP) upon the removal of the water molecule that separates the cation and anion. Studies of sulfate complexes with the use of different techniques (conductometric, potentiometric, and spectroscopic methods, dielectric relaxation spectros copy, ultrasonic dispersion, etc.) bring the authors to contradictory conclusions on the dominant type of complex [3][4][5]. The coordination mode of an anion to a cation in solution (monodentate or bidentate) is also little studied. Different methods were noted to reveal a mixture of inner sphere and outer sphere complexes in aqueous lanthanide and actinide sulfate solutions [3], but there exist disagreements on the dominant type. On the basis of dielectric relaxation measure ments and other literature data, Wachter et al. [4] sup pose that only SSIPs are formed in lithium sulfate solutions, and CIPs are not formed at all even at a con centration of 2 mol/L. A critical view on the possibili ties of spectroscopic methods in the measurements of stability constants of complexes is given in [5] with the use of different metal sulfate complexes as an example.The clarification of a reason for a sharp discrep ancy between the stability constants of 1 : 1 carbonate and sulfate complexes of tervalent lanthanides and actinides in aqueous solutions (the stability constants of carbonate complexes are three to four orders of magnitude higher than those of sulfate complexes) remains to be one of the most intriguing unsolved problems. and anions have close values of crystal ionic radii. Both anions are classified as "hard" according to Pearson's terminology, and tervalent lan thanide and actinide cations are also "hard", so inte rionic interactions are dominantly electrostatic. Close values of the radii of anions with the same charge must have led to close values of stability constants of their complexes (for example, from the viewpoint of Bjer rum's ion association theory, association constants must not differ by more than 10%). An "abnorma...

show abstract

Section: Mishustinsupporting

confidence: 68%

Section: Mishustinmentioning

confidence: 99%