STRUCTURAL STUDIES OF HETEROFULLERENES AND THEIR INTERCALATED DERIVATIVES. Kosmas Prassides* and Fred Wudl** * School of Chemistry and Molecular Sciences, University of Sussex, Brighton BN1 9QJ, UK ** Institute Polymers and Organic Solids, Departments of Chemistry and Materials, University of California, Santa Barbara, CA 93106, USA

The structure of the recently synthesised azafullerene solid has been studied by synchrotron X-ray diffraction both as a function of temperature and pressure. At ambient pressure, the as-prepared solid adopts a hexagonal crystal structure (space group P6(3)/mmc) that persists in the temperature range between 80 and 500 K. Angle-dispersive X-ray diffraction data to pressures in excess of 20 GPa reveal a smooth evolution of the (c/a) ratio which reaches a plateau of 1.633 in the vicinity of 5 GPa. Sublimation of the azafullerene solid leads to a different low-symmetry structural form which shows clear evidence of superlattice formation consistent with the presence of dimeric (C59N)2 units. Reaction of the azafullerene solid with potassium and rubidium leads to the isolation of crystalline derivatives with stoichiometry K6C59N and Rb6C59N. Temperature- dependent synchrotron X-ray diffraction data reveal body-centred-cubic structures, essentially isostructural with the analogous derivatives of C60 and comprising of monomeric (C59N)6- units.