High-yield preparation of endohedral metallofullerenes by an improved DC arc-discharge method

The soot containing endohedral metallofullerenes M-x@C-2n(M=Y, La, Tb and S m; x=1, 2, 3; n greater than or equal to 30) has been prepared by DC are-di scharge method under improved conditions including high helium pressure, lo w electric current, large gap distance between electrodes and high atomic r atio of M/C, with MNi2, alloys instead of metal oxides or pure metals as th e encaged metal source, followed with extraction by CS2. The raw soot and e xtracts were analyzed by laser desorption mass spectrometry and results sho w that the relative yields of metallofullerenes, even if the usually low yi eld ones, Sm@C-74 and Sm@C-84 for example, are rather high. Some possible r easons leading to the high yield preparation are discussed. (C) 2000 Elsevi er Science Ltd. All rights reserved.