NMR Spectra of Oriented Samples of Intercalated Fluorographite and ¹⁹F Chemical Shielding Anisotropy of the CIF₃ Molecule

The analysis of ¹⁹F NMR spectra of polycrystalline and partially oriented samples of fluorinated graphite (C₂F)_n intercalated with chlorine trifluoride has been carried out. Molecular mobility results in almost complete averaging of the dipole-dipole interactions of nuclei, while the essential chemical shielding anisotropy (CSA) is manifested. There is suggested molecular rotation about its C₂ axes, which in turn rotates about the normal to the graphite plane. The CSA (σ_|| - σ_⊥) is determined to be 510 and -640 ppm, respectively, for the two inequivalent fluorine atoms of the molecule. The effect of the "antiparamagnetic" shielding leading to inversion of the chemical shielding tenser [(σ_|| - σ_⊥) < 0] for the equatorial F atom and anomalous line disposition in the NMR spectrum is discussed.