On the so-called “semi-ionic” C–F bond character in fluorine–GIC

Abstract

The short-range structures of fluorine–graphite intercalation compounds with stage-1 structures, C x F ( x = 2.47, 2.84, 3.61), were analyzed by means of neutron diffraction. It has been shown that the so-called “semi-ionic” C–F bond character in C x F is essentially covalent with the bond length of 0.140 nm, and the original planar graphene sheets are buckled at the sp 3-hybridized carbon atoms bound to fluorine atoms. Conjugated C–C double bonds with the bond length of 0.142 nm are preserved between the carbon atoms unbound to fluorine atoms in C x F, while other C–C bonds are single bonds with the bond lengths of 0.153 nm. The C–F bond order in C x F is slightly lower than those in poly(carbon monofluoride) ((CF) n ) and poly(dicarbon monofluoride) ((C 2F) n ), which is explained by the hyperconjugation involving the C–C bonds on the carbon sheets and C–F bond.