Abstract
The observed proton magnetic resonance shifts of ortho-methyl-protons in o-methyl-nitrobenzene derivatives have a regular dependence on the rotational angle of the nitro group around the C-N bond. The nature of this dependence has been mainly attributed to the magnetic anisotropy of the nitro group. From this dependence and with several reasonable assumptions, the principal magnetic susceptibilities of a nitro group have been calculated.