Gas phase abduct of endohedral rare-earth fullerenes Nd@C82 with the ion system of benzene- [Nd @ C82-C6H6] + was observed for the first time by ion-molecular reaction under chemical ionization condition. The possible reaction passageway and molecular structures of this gas phase adduct were discussed and a parallel "reversed umbrella’ π-π interaction complex of the [C6H6]+ ion reacting with the neutral rare-earth fullerenes Nd@C82 was considered to be much reasonable. The experimental result indicated that endohedral rare-earth fullerenes has relatively active relativity and aromatic properties similar towards benzene molecular ion in gas phase.
Endohedral metallofullerene Gd@C2n were synthesized with high-yield using the carbon-arc discharge method of activating the Gd2O3-containing graphite anode in situ and back-burning technique. A series of Cd@C（2n） for 2n from 70 to 96 were effectively extracted by toluene at high-temperature and under high-pressure condition. Gd@C（82）,Gd@C（74） were considered to be fairly stable and soluble metallofullerene species.
The effective preparation of rare-earth metallofullerenes is described. Graphiterod blended with rare earth oxide was used as starting material. The method consists of dou-ble are discharge, extraction with toluene in Soxhlet extractor and extraction with pyridine athigh temperature and pressure. The laser desorption time-of-flight mass spectrometry (LD-TOF MS) results showed that the more important factors influencing the formation of rareearth metallofullerenes appeared the conditions of their preparation and extraction and va-lence states of rare earth elements themselves.
