 In 1973, the dication of hexamethylbenzene, , was produced by Hepke Hogeveen and Peter Kwant.This can be done by dissolving the hexamethyl Dewar benzene monoepoxide in magic acid, which removes the oxygen as an anion.NMR had previously hinted at a pentagonal pyramidal structure in a related cation as had spectral data on the Hogeveen and Kwant dication.