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 [UFn] 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.