Synthesis and Structure of Halogenated Fullerenes

Halogenated fullerenes have been subjects of intensive investigations since the discovery of fullerenes. This paper reviews the synthesis and molecular structures of fullerene halides, covering earlier work in this field and progress in synthetic methods developed in the last few years. The use of inorganic chlorides and oxychlorides as well as (TiCl4 + Br2) mixtures for the chlorination of fullerenes allowed the preparation of new compounds that have been characterized by single-crystal X-ray diffraction, IR spectroscopy, and confirmed by theoretical calculations. The maximum degrees of halogenation and compound stability increase from the bromides to the fluorides. The larger sizes of Cl and Br atoms and the lower C–Hal bond energies account for significant differences in the addition patterns of the C60Haln and C70Halm molecules in relation to those of the fluorides. Investigation of chlorides of lower (C50 – C68) and higher (up to C90) fullerenes contributed significantly to the new chemistry of fullerenes including those with non-IPR and non-classical cages.