Hydrogenselenate der Selten‐Erd‐Elemente: Synthese und Kristallstruktur von La(HSeO4)3 und Gd(HSeO4)(SeO4)

Hydrogenselenates of Rare Earth Elements: Syntheses and Crystal Structures of La(HSeO₄)₃ and Gd(HSeO₄)(SeO₄) Colorless transparent single crystals of La(HSeO₄)₃ (hexagonal, P6₃/m, Z = 2, a = 971.7(1), c = 616.98(8) pm, R_all = 0.0440) were obtained from the reaction of La₂O₃ and conc. selenic acid. La(HSeO₄)₃ is isotypic with the corresponding hydrogensulfate. Its structure can be seen as a variant of the UCl₃ type structure with complex anions and contains the La³⁺ ions in ninefold coordination of oxygen atoms. Single crystals of Gd(HSeO₄)(SeO₄) crystallize from a solution of Gd₂O₃ in selenic acid (70% H₂SeO₄). In the orthorhombic crystal structure (Pbca, Z = 8, a = 920.4(1), b = 1351.6(2), c = 1004.0(1) pm, R_all = 0.0276) the Gd³⁺ ions are coordinated by eight oxygen atoms belonging to four SeO₄^2– and four HSeO₄^– ions. These are surrounded by four Gd³⁺ ions.