Structural study of the ammonium octafluoroneptunate, [NH4]4NpF8

The [NH4]4NpF8 salt was prepared from the solid-state reaction of NpO2 with NH4HF2 and characterized by powder X-ray diffraction and X-ray absorption fine structure spectroscopy. Powder X-ray diffraction confirms [NH4]4NpF8 to be isostructural to [NH4]4UF8. EXAFS analysis indicates the presence of the NpF8 dodecahedron with Np-F = 2.26(1) Å.