Raman, infrared and n.m.r. studies of the graphite hydrofluorides C x F 1-δ (HF) δ (2 ≤ x ≤ 5)

Abstract

Raman spectra of C x F 1-δ (HF) δ ( x /δ ≈ 12) show bands at 1600, 1355 and 839 cm -1 , which are attributed to graphite-like vibrational modes of the carbon atom sheets. The infrared spectra show, in addition to graphite-like bands, absorptions at 1270 and 1100 cm -1 , which are attributed to C-F stretching. Variable contact-time cross-polarized magic-angle spinning 13 C nuclear magnetic resonance spectra (c.p.m.a.s. 13 C n.m.r.) have been obtained for x = 2.05 and 3.70. In both spectra, two peaks ( + 135/10 6 and + 88/10 6 chemical shift from TMS) are seen, which are attributed, respectively, to graphitic and C-F carbons. The ratio of graphitic to C-F carbon atoms has been found to be 1.6(2) : 1 in C 2.05 F 0.82 (HF) 0.18 . The carbon atom sheets in C x F 1-δ (HF) δ appear to be very similar to those in pristine graphite. The bonding of fluorine to carbon is highly ionic. Bonding models are discussed.