Structure of Carbon Monofluoride

Abstract

Ruff and Bretschneider¹, in collaboration with Ebert, reported that the X-ray diffraction pattern of carbon monofluoride, (CF)_n, had similar (hk.0) reflexions to graphite, but that the (000l) and other reflexions dependent on the c or carbon interlayer spacing were absent. From this they assumed that in carbon monofluoride the graphite structure is retained with expansion perpendicular to the carbon layers and, from a determined density of 2·39, calculated the carbon interlayer spacing to be 8·17 A. They postulated that the fluorine atoms acquire electrons from the carbon rings and that the ions so produced lie in a closely packed structure in six parallel layers between each pair of carbon planes requiring a theoretical carbon interplanar spacing of 8·05 A. Although such a structure could reasonably account for the low electrical conductivity and explosive decomposition of the compound, it is very doubtful, as pointed out by Bigelow², whether such an arrangement would have even limited stability. Bigelow proposed an alternative structure in which the fluorine atoms lie in two parallel planes about each plane of carbon atoms, to which they are linked by polarized covalent bonds. Assuming a normal C—F bond of about 1·4 A., the excessively high spacing of 5·3 A. between the planes of fluorine atoms was explained by electrostatic repulsion resulting from the polarization.