[U(NH₃)₁₀]⁴⁺ Cations in Azide, Bromide, and Iodide Ammoniates and a Hydrolysis Product with an unprecedented [U(H₂O)₉]⁴⁺ Cation

Abstract

[U(NH3)10]4+ cations with bicapped square‐antiprismatic coordination spheres were discovered in the compounds [U(NH3)10]I4 ⋅ 17.37NH3, [U(NH3)10]I4 ⋅ 9NH3, [U(NH3)10](N3)4 ⋅ 9NH3, “[U(NH3)10]Br4 ⋅ 9NH3”, and [U(NH3)10]Br4 ⋅ 8NH3 that resulted from reactions of the uranium halides UBr3, UBr4, UBr5, and UI4 with/in anhydrous liquid ammonia (aNH3). Ag+ cations acted as an oxidizing agent and converted U(III) to U(IV), while no oxidation of U(IV) was observed under the experimental conditions. The compound [UBr(H2O)8][U(H2O)9]Br7 ⋅ 2H2O was obtained by unintentional hydrolysis and allowed for the first unambiguous structural characterization of the nonaaquauranium(IV) complex cation [U(H2O)9]4+ by single crystal X‐ray diffraction.