Fullerenide

Fullerenide refers to an anion formed by the addition of one or more electrons to a fullerene molecule. Fullerenes are allotropes of carbon with a spherical, ellipsoidal, or hollow tubular structure, the most famous being buckminsterfullerene (C60). When a fullerene molecule accepts electrons, it becomes a negatively charged ion, known as a fullerene anion or fullerene radical anion. The charge can be delocalized over the conjugated pi system of the fullerene cage.

The most common fullerene anions are C60- and C602-, with one or two added electrons, respectively. Higher charge states, such as C603-, C604-, and even C605-, have also been observed and characterized. The reduction of fullerenes to form fullerides can be achieved through various methods, including electrochemical reduction, chemical reduction using alkali metals or other reducing agents, and photoinduced electron transfer.

Fullerenides exhibit distinct electronic and structural properties compared to neutral fullerenes. For instance, their optical absorption spectra are altered, and their reactivity can change. The study of fullerides is important in areas such as superconductivity, where alkali-metal-doped fullerenes (alkali fullerides) can exhibit superconductivity at relatively high temperatures. They also find applications in organic electronics, catalysts, and as components in advanced materials. The stability of fullerene anions depends on the fullerene cage size and the charge state, as well as the counterions present in the solid state.