NMR evidence forsp3carbon in the low-temperature phase ofLixC60

${\mathrm{Li}}_x{\mathrm{C}}_{60}$ compounds with x between 6 and 15 are investigated using static and magic-angle spinning ${}^{13}\mathrm{C}$ nuclear magnetic resonance spectroscopy. The ${}^{13}\mathrm{C}$ data show evidence for ${\mathrm{sp}}^3$ bonding among ${\mathrm{C}}_{60}$ molecules. The relative intensities of the ${\mathrm{sp}}^3$ sites suggest a ${\mathrm{C}}_{60}$ polymerization and support the prediction of a lattice distortion in the ${\mathrm{Li}}_x{\mathrm{C}}_{60}$ low-temperature phase. The ${}^{13}\mathrm{C}$ chemical shift data indicate an incomplete charge transfer from the Li metal to ${\mathrm{C}}_{60}.$