Gs. Denisov et al., PYRAMIDAL NITROGEN INVERSION HINDERED BY A STRONG INTRAMOLECULAR HYDROGEN-BOND IN 2-DIETHYLAMINOMETHYLPHENOLS, Magnetic resonance in chemistry, 31(11), 1993, pp. 1034-1037
In the H-1 NMR spectra of 2-diethylaminomethyl-3,4,6-trichlorophenol (
1) below 260 K, an additional splitting of the CH2 signal was found, w
hich can be ascribed to the hindered nitrogen inversion. In the molecu
le of the O-methylated derivative (2) this process is fast (on the NMR
time-scale) down to 150 K. The frequencies and the activation paramet
ers of the nitrogen inversion in (1) were measured by DNMR, which indi
cated that the inversion requires a preliminary stage of breaking an i
ntramolecular hydrogen bond. The activation enthalpy, Delta H-inv(doub
le dagger) of the inversion stage was evaluated as 28.5+/-6.7 kJ mol(-
1).