HEXAGONAL CLOSE-PACKED STRUCTURE OF FULLERITE - AN ELECTRON CRYSTALLOGRAPHIC ANALYSIS

The hexagonal close-packed structure of fulferite (C-60:C-70, ca. 9:1), crystallized from benzene, was determined quantitatively from electron diffraction intensity data. The cell constant measured from hko patterns was a = 9.90 +/- 0.04 Angstrom. A correct structure can be found from a multisolution approach, permuting the phase value of the four strongest intensities, where the correct potential map lies among those with the flattest distribution of pixel density. If a model for freely rotating molecules is used in plane group p6m, the final R value is 0.15. On the other hand, disordered comixing of AB and BC layers cannot be supported from these data.