Structure refinement of CsNO3(II) by coupling of 14N MAS NMR experiments with WIEN2k DFT calculations

14N magic-angle spinning NMR spectra are obtained and analyzed for the nitrate ions of the two isomorphous room-temperature phases RbNO3(IV) and CsNO3(II). The analysis reveals that only a single set of 14N quadrupole coupling (CQ, ηQ) and chemical shift anisotropy parameters, corresponding to one NO3- ion, is required for fitting the spectra. This contrasts the published XRD crystal structures, which show the presence of three non-equivalent NO3- ions in the unit cell. WIEN2k DFT calculations of the CQ, ηQ parameters combined with structure optimization (WIEN2k) lead to a refined crystal structure for CsNO3(II) and excellent agreement with the experimental CQ, ηQ values.