In the present work, a theoretical analysis was carried out on the effect of the proximity of a polar bond to a polarizable bond on the magnetic shielding constants of the nuclei belonging to the polarizable bond. In particular, the case of 13C magnetic shielding constants in a vinylic C=C bond is considered. The electric field of the polar bond is simulated by two opposite point charges proximate to the C=C bond in (I) C2H4 and (II) (OH)HC2H2. Changes in the 13C magnetic shieldings as well as the polarization of the φ C=C bond are evaluated as a function of the magnitudes of such point charges. The shielding effect on the C nucleus proximate to the positive charge is of the same order of magnitude as that experimentally determined in aryl methyl ethers. The present analysis yields theoretical support to the assumption that changes in magnetic shielding constants can be adequate probes to detect the stabilization effect in a molecular system originating in an electrostatic interaction between a polar bond proximate to a polarizable bond.
|Number of pages||8|
|Journal||International Journal of Quantum Chemistry|
|State||Published - 1998|