The 1 3 C magic angle spinning NMR spectrum obtained on the Na 4 C 6 0 polymer shows several isotropic resonances accompanied by side bands in the region from 100 to 250 ppm, and a single line at 76ppm. We attribute the former group of lines to inequivalent sp 2 carbons on the C 6 0 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 4 C 6 0 compound, in contrast to the insulating A 4 C 6 0 (A=K, Rb, Cs) fullerides. We also present Raman studies of the Na 4 C 6 0 polymer, which provide clear evidence for charge transfer of four electrons per C 6 0 in the major portion of the sample under consideration, in agreement with X-ray data.