On the Carbon-13 Chemical Shifts of Saturated Hydrocarbons
A molecular orbital interpretation of the carbon-13 chemical shifts of saturated hydrocarbons is presented. The shielding constant of the carbon atom is shown to be roughly proportional to the excess charge densities of 2p electrons, which is in accordance with experiments. The so-called β- and γ-effects in the carbon-13 chemical shifts are explained on the basis of an MO theory.