The Structure And Stability Study On The Endohedral Metallofullerene(EMF)

Endohedral metallfullerenes (EMFs) are kinds of complex molecules that have a metal atom or metal-containing cluster inside hollow fullerene cages. EMFs have attracted widely interesting due to their unique geometric and electronic structures. In the past two decades, quantum chemical computation has particular advantage on investigating the structures and properties of metallofullerenes, such as it can calculate thermodynamics stability of endohedral metallofullerenes efficiently, simulate corresponding spectra dates, and provide theoretical foundations for experimental results. So quantum chemical computation has become indispensable important method in investigating EMFs. In this paper, we carried out systematic investigations on structures and electronic properties of EMFs by means of density functional theory (DFT). The results are summarized as follows:(1) Because of the C and N atomic electron density is similar, single crystal X-ray diffraction can not predict them in the location of the fullerene cage and way of bonding. Based on density functional theory, we studied the structure of endohedral cluster in Sc3CN@Cgo-Ih, determine the structure of their most stable to C atoms in three Sc and N atoms in the middle of the formation of the quasi quadrilateral. In combination with their front orbital diagram, infrared and Raman spectroscopy, further analysis the geometry, electronic structure of Sc3CN@C80-Ih and with the relationship between the Sc3NC@C80-Ih.Through calculation, Sc3CN@C8o-Ih has a larger binding energy and HOMO-LUMO gap, therefore suggests that Sc3CN@C80-Ih more easily than Sc3NC@Cgo-Ih synthesis in the experiment.But both to have consistent Raman and infrared spectrometry, corresponding to the location of the characteristic peak did not change, show the location of the CN to cage distribution does not have significant impact on the overall mechanics.(2) Based on the DFT method to research the new structure of fullerenes YCN@C76structures and properties. By studying its most stable structure and various optical properties, and endohedral metallofullerenes Sc3CN@C80-Ih were compared. Contrast and found that in Sc3CN@C80-Ih, when C in the middle of the endohedral cluster Sc3CN, the structure of Sc3CN@C80-Ih is more stable; however, in linear YCN@C76-19138-C2V, when N in the middle of endohedral cluster YCN, the structure of YCN@C76-19138-C2v is more stable.(3) The research of the paper based on the rule of most stable structures of the C80-Ih carbon cage three metal nitrides endohedral metallofullerenes Sc3_xYxN@C8o (x=0-3). The results show that they have a larger binding energy exothermic and wider HOMO-LUMO energy gap. By calculating their adiabatic electron affinity and ionization potential, we observed Sc3-xYxN@C80(x=0-3) system has large adiabatic electron affinity and is easy to restore. Through analysis of frontier molecular orbital, we mainly concluded the agreement on their valence, and the internal clusters transfer six electron to the cage. On the basis of IR and Raman spectra analysis, the results indicate the difference of Sc3-xYxN@C8o (x=0-3) mainly on endohedral cluster vibration, and the vibration of the C80cage almost remain constant. As the results of the same number of electrons of the endohedral clusters to cage, the electronic structure of the cage keep unchanged and the vibration peak also keep identical. While the endohedral clusters could deviate the position of the corresponding vibration peak because of different radius and stress.