Knowledge Bank

It will be shown that when the origin of the magnetic vector potential is chosen at the electronic centroid of a molecule, it is possible to evaluate a major portion of the paramagnetic part of the proton magnetic shielding constant from a knowledge of the dipole moment, bond distances, and bond angles alone. This formulation has been applied to the molecules $H2,HF,HCl,HBr,HI,LiH,HCN,C2H2,CH4$, and $NH2$. Good agreement is obtained when the results are compared with available data from molecular beam experiments. Application of this method to the evaluation of the paramagnetic part of the magnetic shielding constants of the alkali metals in the alkali halides will also be discussed.