H-1, C-13 AND N-15 NMR-STUDIES ON THE PI-ELECTRON DISTRIBUTION AND INTRAMOLECULAR MOBILITY OF AMINOBUTA-1,3-DIENES

The H-1, C-13 and N-15 NMR spectra of a series of aryl-2-cyano-5-dialk ylaminopenta-2,4-dienenitriles (4 and 5) with different amino and aryl substituents were recorded. The NMR chemical shifts are correlated wi th electronic effects of the substituents on the donor side of the but adiene system and also the para-phenyl substituents X. Dynamic H-1 and C-13 NMR measurements showed rotational processes about the C-2, C-3, C-3, C-4, C-4, C-5 and C-5,N bonds in 4 and 5, the kinetic and thermo dynamic parameters of which were determined by lineshape analysis. The assignment of the lineshape alterations was made on the basis of sign al intensities and separations and from the influence of the donor sub stituents, the phenyl substituents X and the solvents on the energy ba rriers. (C) 1997 John Wiley & Sons, Ltd.