Intercalation of halogen fluorides into graphite

IF₇ intercalates into graphite accompanied by the partial fluorination of the graphite host. The intercalated species was identified as IF₅ by IR and ¹⁹F nmr spectroscopies. Mass spectrometric analyses of the gases evolved from the intercalate showed only IF₅ and fluorocarbons. Iodine pentafluoride intercalates only in the presence of HF, yielding a compound with the stoichiometry C₈IF₅ and no fluorination of the graphite host. Careful elimination of even traces of HF resulted in no intercalation. Evolved gas analysis showed that the only species recovered from the intercalation was IF₅. The remaining interhalogens, ClF₅, ClF₃, BrF₅ and BrF₃ all intercalate into graphite with extensive fluorination of the lattice. In the case of these four compounds, the intercalate proved to be more difficult to characterize, e.g. stoichiometry was often variable, and ¹⁹F nmr yielded resonances that did not agree with any known halogen fluorides. Thermal decomposition of these intercalates showed little or no gas evolution until relatively high temperatures were reached, whereupon Cl₂ or Br₂ was evolved, followed by fluorocarbons.