The evolution of the structure and electronic properties of the fullerene derivatives C60(CF3)n (n=2, 4, 6, 10): A density functional calculation

The generalized gradient approximation (GGA) based on density functional theory (DFT) is used to analyze the evolution of the structure and electronic properties of the fullerene derivatives C-60(CF3)(n) (n = 2, 4, 6, 10). It is found that among the three respective possible stable isomers of C-60 (CF3)(4) and C-60 (CF3)(6), the structure C-60 (CF3)(4) with p-p-p addition and C-60 (CF3)(6) with p-p-p-m-p addition are the most stable structures, respectively. By analyzing the structures of C-60(CF3)(2), C-60(CF3)(4)-1, C-60(CF3)(6)-1, and C-60(CF3)(10), it was found that both the average C-C bond length and the C-C60-C-CF3 bond length increase with the increase of the CF3 number. It was found from the electronic properties of four compounds that the heat of reaction of the compounds almost linearly increases with the number of the CF3, and its maximum appears at n = 6, thus, C-60(CF3)(6) should be the most easily synthesized derivative. It is known from the Mulliken charge that the interaction between CF3 and the cage and the electron transference from CF3 to the cage increase with the number of the CF3. However, the net spins of the compounds are all zero, indicative of their closed-shell electronic structures. Finally, the frontier orbital analysis shows that the electron detaching and attaching both occur at carbon sites of the cage.