Na 4C 60: an alkali-intercalated two-dimensional-conducting polymer

Abstract

The 13 C magic angle spinning NMR spectrum obtained on the Na 4C 60 polymer shows several isotropic resonances accompanied by side bands in the region from 100 to 250 ppm, and a single line at 76 ppm . We attribute the former group of lines to inequivalent sp 2 carbons on the C 60 molecules, and the latter line to sp 3 carbons of the single inter-ball bondings. The electron spin resonance results reveal a metallic behaviour of the Na 4C 60 compound, in contrast to the insulating A 4C 60 (A=K, Rb, Cs) fullerides. We also present Raman studies of the Na 4C 60 polymer, which provide clear evidence for charge transfer of four electrons per C 60 in the major portion of the sample under consideration, in agreement with X-ray data.