The charge distribution in the methoxy -substituted olefins of the series ethylene, methyl vinyl ether, 1,1-dimethoxyethylene, cis- and trans-dimethoxyethylene, tetramethoxyethylene, is discussed on the basis of the 1H and 13C NMR spectra
The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.