Preparation And Chemical Functionalization Of Endohedral Metallofullerenes Containing Yttrium/Praseodymium

Endohedral metallofullerenes(EMFs) containing Y/Pr were synthesized by direct-current(DC) arc discharge method, and the produced soot was extracted with CS2 and trichlorobenzene. Pure endohedral metallofullerenes were obtained by multi-step HPLC isolation,including monometallofullerenes Pr@C82, dimetallofullerenes Y2C2n(n =41-47) and nitride clusterfullerenes Y3N@C2n(n=40,43,44). Each product has been characterized by LDI-TOF mass spectra,UV-Vis-NIR absorption spectra and electrochemical properties.Some products were investigated by the cyclic voltammetry method.The cage structures were speculated through UV-Vis-NIR absorption spectra. Reactivities of some endohedralfullerenes were also studied.The crystal of Pr@C82Ad were grown by diffusion method.Among the endohedralfullerenes systhesized,there are seven metallofullerenes,which are Y2C86,Y2C88,Y2C90(Ⅰ,Ⅱ,Ⅲ),Y2C92,Y2C94(Ⅱ).All UV-Vis-NIR absorption spectra were also made careful comparison with corresponding dimetallofullerenes,carbide and nitride clusterfullerenes reported.The comparabllity of the UV-Vis-NIR absorption spectra indicate that Y2C86 is Y2C2@D2d(51591)-C84,Y2C90(Ⅰ) is Y2C2@ D2(35)-C88.The chemical modification of Pr@C82,Y2C90(Ⅰ),Y2C94(Ⅰ) was investigated.The reactions of Pr@C2v(9)-C82,Y2C90(Ⅰ) with AdN2 have been conducted for the first time,the major products have been separated by HPLC and characterized by LDI-TOF mass spectrum and UV-Vis-NIR spectra. The major products are monoadducts. Similarity of the UV-Vis-NIR spectra between derivatives of Pr@C82 with mother metallofullerenes indicates that these adducts have ring-opened structure.Whereas the different UV-Vis-NIR spectra between derivative of Y2C90(Ⅰ) with mother metallofullerenes suggest that the adduct possess a“closed” cyclopropyl structure. Moreover, the chemical property of Y2C94 was investigated for the first time using 3-triphenylmethyl-5-oxazolidinone,the result of LDI-TOF mass spectrum showed that the derivative was monoadduct.The electrochemical properties of Pr@C82Ad was investigated by the cyclic voltammetry.The results indicated that the mono-adduct had a good oxidation-reduction quality.The X-ray single crystal diffraction study proved that the carbon cages of Pr@C82Ad is C2 V symmetries, The Ad group adds to a [6,6]-bond junction which is close to the encapsulated metal ion. In contrast to those obtained for other M@C82Ad, the crystal structure of Pr@C82Ad showed the disorders.Density Functional Thoery calculations were performed to predict the structures of Pr@C82Ad isomers with the Gaussian 03 program package.Two main products were obtained,which was consistent with the result from experiment.