The Formation Mechanism Of Fullerene C₂ Growth And Theoretical Study On The Detected Sc₂S@C₈₄

In the past 30 years, fullerene has been the focus of nanomaterials research because of the unique physical and chemical properties. The characterization and separation of nearly 100 kinds of fullerenes indicated that fullerenes are a large family and indicates that these species are of unlimited potential applications in many fields such as photovoltaic devices, biomedical, aerospace, photochemical cells and so on. However, a great barrier is that the poor yield and the high production costs which cannot satisfy the growing application requirements. It is foreseeable that in the next few years or even decades that the yield of fullerenes will become one of the most important tasks of fullerene science. And the premise of achieving this goal is to understand the mechanism of fullerene formation. Here the formation mechanism of C2 growth of fullerene is computationally studied; in addition, the structure and properties of new species Sc2S@C84 are characterized theoretically.1) The formation of metallic sulfide fullerene Sc2S@C82 via bottom-up road and isomerizationDensity functional theory (DFT) calculations are performed to identify the favored isomers of Sc2S@C82 in terms of thermodynamic and kinetic stability. Then, the formation of Sc2S@C82 was studied based on the closed network growth model and the interconversion of Sc2S@C82. The calculations demonstrate that two pathways may be occurred from Sc2S@C80-D5h(31923), and the favored pathway is via intermediate Sc2S@C82-Cs(39704) instead of the most well-known Sc2S@C82-Cs(39663). Furthermore, the interconversion between Sc2S@C82-Cs(6) and Sc2S@C82-C3v(8) is proved to be a reversible process. These calculations can rationalize the experimental observations and put insights into the formation of other metallofullerenes.2) Theoretical study on the detected Sc2S@C84Sc2S@C84 has not been characterized structurally. DFT calculations show that Sc2S@C84 and Sc2C2@Cs4 shared the same parent cage; in addition, a IPR-violating isomer Sc2S@C84:51383, which is the second lowest in energy with a largest HOMO-LUMO gap in all isomers, indicating higher kinetic stability. The analysis also show that the isomer Sc2S@C84:51575 can convert into isomer Sc2S@C84:51591 at temperatures above 2800K. Molecular orbital analysis indicates both Sc2C2 and Sc2S formally transfer 4 electrons to the parent cage. QTAIM analysis demonstrates that there is a covalent interaction between Sc2S and C84:51591. The IR spectra of the Sc2S@C84 are also provided to help the future structural identification.