DISCRETE LAYERS OF ORDERED C-60 MOLECULES IN THE COCRYSTAL C60.CH2I2.C6H6 - SYNTHESIS, CRYSTAL-STRUCTURE, AND C-13 NMR PROPERTIES

The first crystals containing crystallographically ordered (at room temperature) unmodified fullerene (C60) molecules, with chemical composition C60.CH2I2.C6H6, have been prepared. The fullerene molecules are arranged in novel hexagonally close-packed layers, separated by the solvent components. A monoclinic (space group C2/c) crystal structure of C60.CH2I2.C6H6 was determined at room temperature [lattice parameters: a = 21.239 (7) angstrom, b = 17.403 (4) angstrom, c = 10.106 (2) angstrom, beta = 106.03 (2)-degrees, V = 3590 (2) angstrom3] and at 122 K [a = 21.024 (7) angstrom, b = 17.298 (4) angstrom, c = 10.043 (2) angstrom, beta = 105.93 (2)-degrees, V = 3512 (2) angstrom3]. The ordered nature (on the X-ray time scale) of the compound allows a detailed determination and discussion of the intermolecular interactions between neighboring fullerene molecules as well as between the C60 and the solvent molecules. Solid-state C-13 NMR under MAS shows three distinct resonances for C60, benzene and CH2I2; static NMR measurements set a lower limit for the rate of molecular rotation of C60 on a time scale of tens of microseconds.