Knowledge Bank

A theoretical justification is given for partitioning the individual elements in the total magnetic susceptibility tensor $(Xaa,Xbb,andXcc)$ into local contributions. Molecular data is analyzed to give local values of $Xaa,Xbb,andXcc$ for either atoms or bonds. These values can be added to give the total molecular magnetic tensor elements for a wide range of non-strained, non-aromatic compounds. The method is used to determine relative aromaticities, interpret data from the Cotton-Mouton experiments, and also to gain information about molecular structure. The values given here are also of use in determining the neighbor group effects on proton magnetic shielding.