Deshielding of carbon-13 nuclei by attached iodine atoms. Solvent effects on carbon-13 chemical shifts in alkyl iodides

Abstract

Deshielding of carbon-13 nuclei occurs upon replacement of hydrogen by iodine at secondary and tertiary carbon atoms and may be related to the low electron density at the carbon atom as a consequence of the highly ionic character of the C–I bond in these cases; large solvent effects occur at the carbon atom directly bonded to iodine and affect substituent-effect parameters, the solvent shift varies linearly with the Onsager reaction-field.