MASS-SPECTRAL STUDY OF EXTRACTABLE LA-CONTAINING AND LU-CONTAINING FULLERENES

Mass spectra of LaxC2n (x = 1,2), well known endohedral metallofullere nes, and Lu2C2n (2n = 76-112), new members of extractable metallofulle renes, were studied. Positive-ion laser desorption/ionization (LDI) an d electron impact (EI) mass spectra indicated that lutetium is a speci al lanthanide that prefers to form dilutetium fullerenes by the are-bu rning method. However, the signals for Lu2C2n become very weak in nega tive-ion LDI-MS, this is different from La-2@C-80, which has close rel ative abundances in positive- and negative-ion MS. The distinction bet ween Lu2C2n and La-2@C-80 in the negative-ion LDI mass spectra may be due to the different structures of La- and Lu-containing fullerenes. ( C) 1997 by John Wiley & Sons, Ltd.