Investigations of Uranyl Fluoride Sesquihydrate (UOF·1.57HO): Combining F Solid-State MAS NMR Spectroscopy and GIPAW Chemical Shift Calculations.

High-resolution F magic-angle spinning (MAS) NMR spectra were obtained for the uranium-bearing solid uranyl fluoride sesquihydrate (UOF·1.57HO). While there are seven distinct crystallographic fluorine sites, the F NMR spectrum reveals six peaks at -33.3, 9.1, 25.7, 33.0, 39.0, and 48.2 ppm, with the peak at 33.0 ppm twice the intensity of all the others and therefore corresponding to two sites. To assign the peaks in the experimental spectra to crystallographic sites, F chemical shifts were calculated using the gauge including projector augmented waves (GIPAW) plane-wave pseudopotential approach for a DFT-optimized crystal structure. The peak assignments from DFT are consistent with two-dimensional double-quantum F MAS NMR experiments.