Synthesis and structural assessment of ammonium and caesium difluorodioxoperoxouranates(VI), A2[UO2(O2)F2](A = NH4 or Cs), and alkali-metal difluorodioxoperoxouranate(VI) monohydrates, A2[UO2(O2)F2]·H2O (A = K or Rb)

Abstract

The product obtained by treating an aqueous solution of UO₂(NO₃)₂·6H₂O with NH₄OH or KOH reacts with AF (A = NH₄, Rb, or Cs) or KF, 30% H₂O₂, and a very small amount of 40% HF, in the mol ratio UO₂(NO₃)₂·6H₂O:AF:H₂O₂ of 1:4:110.8, at pH 6.5–7 to afford ammonium and caesium difluorodioxoperoxouranates(VI), A₂[UO₂(O₂) F₂](A = NH₄ or Cs), and potassium and rubidium difluorodioxoperoxouranate(VI) monohydrates, A₂[UO₂(O₂)F₂]·H₂O (A = K or Rb). The i.r. spectra suggest that the peroxo-ligand is bonded to the UO₂²⁺ centre in a triangular bidentate (C_2v,) manner.