Evaluation of the stability constants of uranyl association complexes with chloride, fluoride, bromide, and sulfate anions in solutions of constant ionic strength

Halide Abstraction from Halogenated Acetate Ligands by Actinyls: A Competition between Bond Breaking and Bond Making

“…High actinide halide BDEs, BDE­[An–X] (An = U, Np, Pu; X = F, Cl, Br), have been demonstrated by the ability of bare An + ions to abstract halogens from halogenated hydrocarbons. , A particular area of interest is complexes that comprise the actinyls, AnO 2 2+ , bound to one or more halide: AnO 2 X n (2‑ n )+ . ,− One motivation for studying such simple complexes is that the effective electron donation of halides to the actinide metal center affects the axial actinide-oxygen bonds, generally weakening them. − Uranyls, both U VI (unless otherwise specified the oxidation states hereafter are An VI ) and U V , have been shown to form various halide complexes in condensed and gas phases, , including as representative examples UO 2 X 3 – (X = F, Cl, Br, I), ,, UO 2 F n (2‑ n )+ ( n = 1–4), − UO 2 Br 4 2– , U V O 2 X (X = Cl, I), and UO 2 X 2 (X = Cl, Br) . It has been established that the complexation affinities of uranyl by halides decreases in the order F – > Cl – > Br – . The reported synthesis of neptunyl and plutonyl halide complexes is substantially more limited and has focused primarily on the more highly Lewis basic fluoride and chloride ligands. , Among the reported neptunyl halide complexes are NpO 2 F 2 , − Np V O 2 F, , Np V O 2 F 2 – , and NpO 2 Cl 4 2– .…”

“…25 It has been established that the complexation affinities of uranyl by halides decreases in the order F − > Cl − > Br − . 26 The reported synthesis of neptunyl and plutonyl halide complexes is substantially more limited and has focused primarily on the more highly Lewis basic fluoride and chloride ligands. 27,28 .…”

Quenching Mechanism of Uranyl(VI) by Chloride and Bromide in Aqueous and Non-Aqueous Solutions

“…By fitting the PARAFAC normalized speciation data by least-square parameter optimization (fmincon, Matlab) of symbolically solved complex equilibria (symbolic toolbox, Matlab), we received fitted extinction coefficients ε and complex stability constants β 1 for both ligand samples. We can see that for the first complex stability constant β 1 , chloride ions form a 10 times’ weaker complex than with bromide, 2.0 M –1 (Soderholm/NEA-Database: 1.5 m –1 at I = 5.3 m –1 ) compared to 20 M –1 (Razik: 65 m –1 at I = 0.05 M –1 ), respectively.…”