Electronic properties of doped fullerenes

The most abundant fullerene molecule, C₆₀, has just the right combination of size, chemical stability, and activity to serve as the building block for a large variety of solids with fascinating properties. After a short overview of the related carbon compounds, first the structures of the C₆₀ molecule and the pure crystalline C₆₀ are summarized. Experimental and theoretical works on the vibrational and the electronic properties of the molecule and the solid are reviewed. Next, some of the relevant concepts widely used in solid state phyics, like electron-phonon and electron-electron interactions, Hund's rule and Jahn-Teller distortion are discussed in the context of doped fullerides. The structural and electronic instabilities of the conducting C₆₀ compounds are reviewed in detail. Finally, a few open questions are discussed.