Raman spectroscopy and X-ray diffraction studies of the single- and double-bonded two-dimensional polymers NanLi4–nC60 Original Research Article

We have examined intercalated compounds of C60 containing four light alkali metal atoms per molecule. The single-metal compounds Na4C60 and Li4C60 form two-dimensional polymers with intermolecular links consisting of one and two C–C bonds, respectively. We have here studied the compounds NanLi4−nC60 (n=0,1,…,4) to find out what parameters define the polymeric structure, in particular the type of intermolecular bonding. The materials have been studied by X-ray diffraction and Raman spectroscopy. Although the results are compatible with a charge transfer model with different charge transfers for Na and Li ions, other models cannot be ruled out because disorder and mixed phases complicate the analysis.