Theoretical Studies on the Substitution Patterns in Heterofullerenes C70-xNx and C70-xBx (x = 2−10)

Abstract

Possible structures of heterofullerenes C60-xNx and C60-xBx (x = 2−8) have been calculated using semiempirical MNDO, AM1, PM3, and ab initio methods in order to determine the most stable structures, to investigate the underlying cause of their stabilities, and to predict their electronic properties. The calculation results indicate that the N-doped fullerenes are more stable than their B-doped analogues, but both are less stable than C60 thermodynamically, and the stabilities decrease with increasing number of the heteroatoms. The most likely structures of the heterofullerenes investigated in this paper are determined; it is found that there is a fair correlation between the regioisomerism of N- or B-doped fullerenes and that of fullerene adducts. It is proposed that the changes of hybridization from sp2 to sp3 are the predominant factors of the regiochemistry for both heterofullerenes and fullerene adducts, which leads to the existence of this unexpected correlation. This regioisomerism correlation makes...