13C NMR study of Ca@C74:: the cage structure and the site-hopping motion of a Ca atom inside the cage

The C-13 NMR spectra of Ca@C-74 have been measured at 22 and 70 degreesC. The cage symmetry is assigned to be D-3h. Two distinct features of the C-13 NMR spectra, different linewidths of each line and line sharpening at higher temperature, indicate that the Ca atom hops between the several stable sites inside the D-3h cage. (C) 2004 Elsevier B.V. All rights reserved.