Theoretical Study Of The Fullerene Derivatives

In this paper, semi-empirical (AM1) and density functional theory (DFT) calculations were performed on fullerenes derivatives C60X18, C70X10 and C80X12(X=H, F, C1 and Br) to put insight into the relationship between their structures and stabilities.This paper includes the following two parts:1. AM1 and DFT calculations were performed on fullerenes derivatives C60X18 and C70X10 (X=H, F, Cl and Br) constructed from IPR-C60, IPR-C70, non-IPR C60 containing 18 active sites and non-IPR C70 containing 10 active sites. The calculated results show that the lowest energy isomers are IPR-satisfying for C60X18(X=H, F, Cl and Br). It is found that the addition patterns of X (X=Cl and Br) are different from those of X (X=H and F) for C60, demonstrating that the stability of fullerene derivatives is partly attributed to the steric repulsion and electronegativity of added atoms. However, the lowest energy isomers are IPR-violating for C70X10 (X=H, F and Cl) and the most favorable structure of C70Br10 is IPR-satisfying. And the pyrimidization angle and distortion of angle viewpoint cannot rationalize these calculated results. All this suggest that many more fullerene derivatives may violate the isolated pentagon rule.2. Density functional theory calculations were performed on C80X12(X=H, F, Cl, Br) to gain insight into their structures and stability. The results demonstrate that the lowest energy isomers are IPR-violating for C80X12(X=H, F), however, for C80X12(X=Cl, Br), the lowest energy isomers are IPR-satisfying. Since the van der Waals radius of H and F atoms are small, the resulting steric strain among added atoms is slight or negligible for C80X12(X=H, F), the lowest energy structures are those with the H and F atoms bonded to the carbon atoms of the fused pentagons. However, Cl and Br atoms tend to bond to 1,4-cites to avoid strong steric repulsion. The calculated results also reveal tha t the order of the energy of reaction C8o+6X2→C8oX12(X=H, F, Cl, Br) is C80F12> C8oCl12> C80H12> C80Br12. These calculated results suggest that the stability and addition patterns of fullerene derivatives are also related to the radius and electronegativity of added atoms.