Unusual observation of nitrogen chemical shift anisotropies in tetraalkylammonium halides by 14N MAS NMR spectroscopy

Solid‐state 14N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

“…Moreover, the value for CH 3 3 C 6 H 5 NI is about an order of magnitude larger than for CH 3 4 NI (C Q D 31.7 kHz). 5 As might be expected, this shows that substitution of a phenyl C 6 H 5 group for a methyl CH 3 group directly onto the ammonium nitrogen has a larger influence on the magnitude of C Q when compared to the effect of substituting the phenyl group for one of the hydrogen (H) atoms in CH 3 Table 1 for the single N-site in CH 3 3 C 6 H 5 NI.…”

“…zeolites 11 ) and the unusual observation of a 14 N chemical shift anisotropy (CSA) present in some symmetrical tetraalkylammonium salts. 5 Only a few cases of NH 4 C salts exhibiting a large number of 14 N MAS sidebands, which allow determination of quite large C Q ( 14 N) values and the associated Á Q parameter, have been published. 3 The present work demonstrates an advancement in the application of solid-state 14 N MAS NMR to the important class and wide range of ammonium salts.…”

Direct detection of nitrogen-14 in solid-state NMR spectroscopy

“…Changes in the EFG parameters and isotropic shifts occurred for both species at the phase transition, and a hysteresis in the transition was observed. Elsewhere, 14 N CS parameters for some tetralkylammonium halides were measured from the MAS spectra, with 1 H decoupling applied [110]. The relatively small C SAs (a few tens of p pm) caused significant asymmetries in the 14 N spinning sideband manifolds, and careful experimental 38 optimization proved that such asymmetries were not experimental artifacts.…”

“…4c). This effectively amplifies the effects of the CSA on the 14 N spectrum [110]. The nitrogen CSA in lead nitrate could also be extracted from the individual sideband lineshapes in its 14 N MAS spectrum [111].…”

Perspectives in 1H, 14N and 81Br solid-state NMR studies of interfaces in materials textured by self-assembled amphiphiles

“…In contrast to several nitrogen containing organic groups, tetraalkylammonium compounds give rise to moderate 14 N quadrupolar coupling constants C Q (in the 100 kHz range), which allow a direct observation of 14 N resonances in conventional MAS spectra [91,92]. We have undertaken a systematic study of n-alkyltrimethylammonium bromide crystals of different chain length (from 12 to 16 carbons) and compared their spectra to that of smaller tetraalkylammonium salts [93].…”