The Heaviest Possible Ternary Trihalogen Species, IAtBr-, Evidenced in Aqueous Solution: An Experimental Performance Driven by Computations.
Evidencing new chemical species in solution is particularly challenging when one works at ultra-trace concentrations, as is likely to happen with radioelements such as astatine (Z=85). Herein, quantum mechanical calculations were used to predict the narrow experimental domain in which it is possible to detect the presence of an exotic ternary trihalogen anion, IAtBr-, and thus to guide a series of experiments. By analyzing the outcomes of competition experiments, we show that IAtBr-exists and can even predominate in aqueous solution. The equilibrium constant associated with the reaction At++I-+Br-⇌IAtBr-was determined to be 107.5±0.2, which is in fair agreement with that predicted by density functional theory (106.9). This system not only constitutes the very first example of a ternary trihalogen species that involves the element astatine but is also the first trihalogen species reported to predominate in solution. Moreover, we show that the oxidation number of At is zero in this species, as in the other molecules and anions that At+can form with Cl-, Br-, and I-ligands.
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.
Ning
N
Guo
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.|CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44302, Nantes Cedex 3, France.
Dumitru-Claudiu
DC
Sergentu
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.
David
D
Teze
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.
Julie
J
Champion
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.
Gilles
G
Montavon
CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44302, Nantes Cedex 3, France.
Nicolas
N
Galland
SUBATECH, UMR CNRS 6457, IN2P3/Mines, Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307, Nantes Cedex 3, France.
Rémi
R
Maurice
astatine; competition experiments; density functional calculations; halogens; ternary trihalogen species