Polymeric fullerenes

Structures, preparation, and physical properties of intrinsic polymeric fullerenes are reviewed. Three routes to the polymeric state are considered: polymerization by light, pressure, and charge transfer. For all three processes different types of polymers are known. Polymerization by charge transfer is discussed for AC(60), A = K, Rb, Cs. The systems for Rb and Cs are quasi-1D metallic at room temperature. KC60 is either 3D metallic or phase separates into K3C60 and C-60. Below 50 K RbC60 and CsC60 are insulators due to a spin density wave transition. The electron-phonon coupling for the molecular modes is unexpected low in the metallic state which is probably the reason for the lack of superconductivity in these systems.