Low-temperature synchrotron radiation study of a twinned disordered crystal of bis(4,4′-bromophenyl)-61,61-diyl methano fullerene C60

Synchrotron radiation diffraction measurements at 100 (5)K have been carried out on bis(4,4'-bromophenyl)-61,61-diyl methano fullerene C-60 using area detector technology. In order to obtain a satisfactory description of the data it is necessary to introduce both a twinning model of the crystal and a disorder model consisting of two different isomers of the title compound. The study provides the first solid-state characterization of a 6-5 isomer of a methano fullerene. For the 6-6 isomer the geometry is in good agreement with recent literature on methane fullerenes. Unfortunately, the present study cannot resolve the bond lengths in the transannular region. The fact that the structure can be solved from diffraction data measured on a minute poorly scattering crystal shows that the low-temperature single-crystal synchrotron radiation technique is an indispensable tool in chemical crystallography.