Advances on the Determination of the Astatine Pourbaix Diagram: Predomination of AtO(OH)(2)(-) over At- in Basic Conditions

作者：Sergentu Dumitru Claudiu; Teze David; Sabatie Gogova Andrea; Alliot Cyrille; Guo Ning; Bassal Fadel; Da Silva Isidro; Deniaud David; Maurice Remi; Champion Julie; Galland Nicolas^*; Montavon Gilles^*

来源：Chemistry - A European Journal, 2016, 22(9): 2964-2971.

DOI：10.1002/chem.201504403

• astatine
• competition experiments
• hydrolysis constants
• Pourbaix diagrams
• quantum mechanical calculations

It is generally assumed that astatide (At-) is the predominant astatine species in basic aqueous media. This assumption is questioned in non-complexing and non-reductive aqueous solutions by means of high-pressure anion-exchange chromatography. Contrary to what is usually believed, astatide is found to be a minor species at pH=11. A different species, which also bears a single negative charge, becomes predominant when the pH is increased beyond 7. Using competition experiments, an equilibrium constant value of 10(-6.9) has been determined for the formation of this species from AtO(OH) with the exchange of one proton. The identification of this species, AtO(OH)(2)(-), is achieved through relativistic quantum mechanical calculations, which rule out the significant formation of the AtO2- species, while leading to a hydrolysis constant of AtO(OH) in excellent agreement with experiment when the AtO(OH)(2)(-) species is considered. Beyond the completion of the Pourbaix diagram of astatine, this new information is of interest for the development of At-211 radiolabeling protocols.

• 出版日期2016-2-24