The mercury cation Hg2+ is used to intercalate NbF−6 and TaF−6 anions into pyrolytic graphite (HOPG). The Hg2+ cation in Hg (NbF6)2 and Hg(TaF6)2 oxidizes HOPG to form stage-3 compounds. The Hg2+2 cation is also used as an oxidant to intercalate AsF−6 and SbF−6 ions into graphite. The reduced products of the reactions are identified by Raman spectra. The intercalation compounds are characterized by (00
l) x-ray diffraction, and the intercalants are identified with mass spectrometer analysis.