The stability constants of chloride complexes of mono-valent astatine in nitric acid solution

Norseyev, Yu. V.; Khalkin, V.A.

doi:10.1016/0022-1902(68)80118-6

Cited by 21 publications

(22 citation statements)

References 1 publication

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“…In acidic conditions and in the presence of dichromate, there is no doubt about the presence of another “metallic” compound. It holds a positive charge, as evidenced by electromobility experiments, and it forms complexes with anions. − The nature of species III remains, however, unknown, and several forms are proposed: At + , AtO + , and At 3+ . − Some authors have attempted to identify the nature of the cationic form by comparing its behavior with inorganic sorbents with that of model cations. For example, Rössler et al proposed At + considering the difference in retention volumes obtained by HPLC on Aminex A7 cation-exchange resin between species III and Tl + .…”

Section: Discussionmentioning

confidence: 99%

Astatine Standard Redox Potentials and Speciation in Acidic Medium

et al. 2009

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A combined experimental and theoretical approach is used to define astatine (At) speciation in acidic aqueous solution and to answer the two main questions raised from literature data: does At(0) exist in aqueous solution and what is the chemical form of At(+III), if it exists. The experimental approach considers that a given species is characterized by its distribution coefficient (D) experimentally determined in a biphasic system. The change in speciation arising from a change in experimental conditions is observed by a change in D value. The theoretical approach involves quasi-relativistic quantum chemistry calculations. The results show that At at the oxidation state 0 cannot exist in aqueous solution. The three oxidation states present in the range of water stability are At(-I), At(+I), and At(+III) and exist as At(-), At(+), and AtO(+), respectively, in the 1-2 pH range. The standard redox potentials of the At(+)/At(-) and AtO(+)/At(+) couples have been determined, the respective values being 0.36 +/- 0.01 and 0.74 +/- 0.01 V vs NHE.

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Section: Discussionmentioning

confidence: 99%

Astatine Standard Redox Potentials and Speciation in Acidic Medium

et al. 2009

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“…a strong affinity between At(x) + and the counter-ion. This is however improbable since: (i) ClO 4 − is generally considered as a non complexing agent for cations [23]; (ii) The thermodynamic constants describing the interaction between At(x) + and NO 3 − [23] and Cl − [23,24] are not sufficiently high to allow a complete astatine complexation.…”

Section: Astatine Extraction From Various Acid Mediamentioning

confidence: 99%

Extraction of astatine-211 in diisopropylether (DIPE)

et al. 2009

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The extraction mechanism of astatine-211 in diisopropylether (DIPE) is studied by analyzing the effect of the nature of the aqueous solution and organic solvent on the distribution coefficients characterizing the ratio of organic and aqueous concentration of astatine (D). On the one hand, at a given pH value, D was shown to be independant of the nature and concentration of the counter-ion present in the aqueous solution (Cl-, ClO4-, NO3-). On the other hand, the nature of the organic solvent had a strong effect. D increases as the polarity of the organic solvent increases. These experimental observations are explained by the solvation of astatine by the organic solvent. The back-extraction of astatine from the organic to the aqueous phase is efficient in basic conditions. This is explained by the formation of a hydrolyzed species of astatine presenting no affinity for DIPE. Hydrolysis constants of astatine are deduced from experimental data (logβ1=-3.0±0.1 and logβ2=-14.2±0.1)

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“…Several papers have shown the formation of complexes between AtO + and simple organic and inorganic ligands. , Some structural parameters were recently determined by (quasi) relativistic quantum calculations for the complexes AtOX and AtOX 2 – , with X = Cl, SCN, and Br . It has been shown by electromigration in noncomplexing medium (H/NaClO 4 ) that AtO + reacts with water above pH 1. ,− The mobility of the species decreases when the pH increases until it equals 0 above pH 6.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Astatine(III) Hydrolyzed Species: Experiments and Relativistic Calculations

et al. 2013

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This work aims to resolve some controversies about astatine(III) hydroxide species present in oxidant aqueous solution. AtO(+) is the dominant species existing under oxidizing and acidic pH conditions. This is consistent with high-performance ion-exchange chromatography data showing the existence of one species holding one positive charge. A change in speciation occurs as the pH changes from 1 to 4, while remaining under oxidizing conditions. Dynamic experiments with ion-exchange resins evidence the existence of a neutral species witnessed by its elution in the void volume. Batch-experiments using a competition method show the exchange of one proton indicating the formation of the AtO(OH) species. The hydrolysis thermodynamic constant, extrapolated to zero ionic strength, was determined to be 10(-1.9). This value is supported by two-component relativistic quantum calculations and therefore allows disclosing unambiguously the structure of the formed species.

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The stability constants of chloride complexes of mono-valent astatine in nitric acid solution

Cited by 21 publications

References 1 publication

Astatine Standard Redox Potentials and Speciation in Acidic Medium

Astatine Standard Redox Potentials and Speciation in Acidic Medium

Extraction of astatine-211 in diisopropylether (DIPE)

Investigation of Astatine(III) Hydrolyzed Species: Experiments and Relativistic Calculations

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