Replay of amide type resonance in 6-[(dimethylamino)methylene]1,3-dimethylaminouracil: A dynamic NMR and density functional theory study

Dynamic 1H NMR spectroscopy has been used to determine the C–N rotational barrier of 6-[(dimethylamino)methylene]1,3-dimethylaminouracil in 1,1,2,2-tetrachloroethane-d2. Theoretical calculations show that the origin of this barrier lies in the formation of partial C–N double bond in the ground state. The computed barrier (19.8 kcal/mol) is in excellent agreement with the observed value (18.97 kcal/mol). The uracil ring is found to have no effect on the barrier.