Semi-ionic C-F bond

Semi-ionic C-F bonding in Cj,F is also supported by the long (2.1—2.2 A) C-F bond lengths suggested by structural models for C5F, C3F, and CjF. In these packing models the carbon- and fluorine-atom van der Waal s radii are taken as 1.67 and 1.33 A, respectively. The fluorine atoms are distributed evenly over the carbon atoms of the planar eclipsed sheets and the C-F bond length varies to produce the observed c-spacing. 

Fluorination of natural graphite powder (x4 pm) by a gas mixture of F2, HF and IF5 yielded high fluorine content samples, CF0.8, CF0 9 and CF] 0 [34]. The structural parameters obtained by X-ray diffraction were 7C = 0.59 nm and oq = 0.246 nm. XPS data indicated the existence of two Cls peaks at 287.0 eV and 289.4 eV, and one F]S peak at 688.0 eV, which are intermediate values between those for semi-ionic and covalent C—F bonds. Galvanostatic discharge of these CFV samples was done... 

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