Culcalative Study Of The Non-classical Fullerenes And The Hydrides Of Non-classical Fullerenes

In this paper, Hartree-Fock (HF) and density functional theory (DFT) calculations were performed on non-classical fullerenes C₅₀-C₇₀ and their hydrides to put insight into the relationship between the geometrical structures and stability.This paper includes the following three parts.1. HF and DFT calculations were performed on non-classical fullerenes C₆₁-C₇₂ with square (s) and their hydrides constructed from I_h-C₆₀,1809-C₆₀ and 1810-C₆₀. The calculated results show that those structures with squre(s) embedded are much more stable than the corresponding ones with square(s) attached. Furthermore, the number of fused pentagons is a factor determing the stability of non-classical fullerenes and their derivatives. Structural analysis demonstrates that the carbon atoms linking the cage and the square form more distorted sp3 hybridization than those in the former structures although both kinds of structures contain same strained square(s), indicating that 0-0 repulsion play an important role in determining the stability of these non-classic fullerenes and their derivatives.2. HF and DFT calculations were performed on the hydrides of non-classical fullerenes C₅₂-C₅₈ constructed from 13- C₅₀, 43- C₅₀, 181-C₅₀,256-C₅₀, 270-C₅₀, and 271-C₅₀. The calculated results demonstrate that those structures with square(s) embedded are all more stable than the ones with square(s) attached and the well-known pyrimidization viewpoint cannot rationalize these calculated results. Structural analysis demonstrates that the carbon atoms at the fusion of the cage and the square form more distorted sp³ hybridization than those carbon atoms of square embedded. These calculations demonstrate that the distortion of the angles of sp³ carbon atom can be an index for evaluating the stability of the derivatives of a fullerene or fullerene-like structure.3. DFT calculations were performed on the hydrides of all classical isomers of C₅₈ with 18 active carbon atoms and two non-classical isomers of C₅₈ with a heptagon. The calculated results show that C_s-C₅₈H₁₈ with a heptagon is much more stable than 102 classical C₅₈H₁₈, furthermore, some active carbon atoms at the fused pentagons do not bond to H atom in the two non-classical structures. These calculations demonstrate that the stability of fullerene hydrides is determined by both geometrical and electronic factor.