Expanding pentafluorouranates: hydrothermal synthesis and characterization of β-NaUF5 and β-NaUF5·H2O

Abstract

Two new sodium uranium(IV) pentafluorides were synthesized from uranium dioxide, HF, and NaF using mild hydrothermal conditions. β-NaUF₅·H₂O has greater lattice energy than previously-known α-NaUF₅·H₂O and possesses lower symmetry with the latter compound being orthorhombic, whereas β-NaUF₅·H₂O is monoclinic. Trigonal β-NaUF₅ also possesses different connectivity between the [UF_n] building units than the α-phase, with higher symmetry and greater lattice energy than orthorhombic α-NaUF₅. The single crystal absorption spectra of these compounds are also reported and compared.