Nitrogen-15 chemical shift measurements carried out under NO at 1 atm and pH ≥ 2.2 yield the value Δ(δ15N) = −30.4 ppm for the total protonation shielding of NO2−(aq). Measurements at higher acidity levels reflect the increasing significance of NO+ and confirm the presence of two 15N resonances, one sharp and one broadened, in the region around 45% D2SO4. Assignment of the sharp peak to NO+ is confirmed by solid-state NMR of NOBF4. Broadening in the other suggests that exchange between HNO2 and some form of acidium ion (e.g. H2NO2+) precedes NO+ release, but no NOE is detected in 42.4% D2SO4 and it is inferred that no proton-to-nitrogen connnectivity occurs in this species. Nitrogen-15 chemical shifts and chemical shift anisotropics have been obtained in the solid state at natural isotopic abundance for the nitrosonium and nitronium ions in their respective tetrafluoroboride salts.
|Original language||English (US)|
|Number of pages||4|
|State||Published - 1993|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry