Solid-State 17O NMR of Oxygen-Nitrogen Singly Bonded Compounds: Hydroxylammonium Chloride and Sodium Trioxodinitrate (Angeli's Salt)

We report a solid-state NMR study of O-17-labeled hydroxylammonium chloride ([(HO)-O-17-NH3]Cl) and sodium trioxodinitrate monohydrate (Na-2[(ONNO2)-O-17]center dot H2O, Angelis salt). The common feature in these two compounds is that they both contain oxygen atoms that are singly bonded to nitrogen. For this class of oxygen-containing functional groups, there is very limited solid-state O-17 NMR data in the literature. In this work, we experimentally measured the O-17 chemical shift and quadrupolar coupling tensors. With the aid of plane-wave DFT computation, the O-17 NMR tensor orientations were determined in the molecular frame of reference. We found that the characteristic feature of an ON single bond is that the O-17 nucleus exhibits a large quadrupolar coupling constant (13-15 MHz) but a rather small chemical shift anisotropy (100-250 ppm), in sharp contrast with the nitroso (O=N) functional group for which both quantities are very large (e.g., 16 MHz and 3000 ppm, respectively).