Diamagnetic anisotropy of some organic molecules

Abstract

The diamagnetic anisotropies of crystals of aromatic and aliphatic compounds, mostly of known structure, have been measured, and the principal molecular susceptibilities deduced from these and the molecular orientations. In a few cases where the absolute susceptibility is not known with certainty, the molecular anisotropy may, nevertheless, be calculated with a good degree of accuracy. The molecular susceptibilities and anisotropy are related to the molecular shape and constitution, and to the bond character; and in the case of aromatic compounds they are strongly influenced by substitution, which, in general, markedly decreases the anisotropy. This decrease varies not only with the nature of the substituents (heavy atom, compact group or aliphatic chain) but with their positions on the nucleus. This may give some information concerning the effect of substitution on conjugation, especially when correlated with changes in bond lengths and angles.