C_(70)S可能异构体的结构与稳定性的理论研究

Theoretical studies on the structures and stability of various possible isomers of C_(70)S

分别用半经验的AM1,PM3及MNDO方法研究了富勒烯衍生物C70S的12种可能异构体的结构和稳定性.计算结果表明:S原子加成在4种6—6键上的稳定构型中,非赤道带6—6键加成的三个异构体为闭环结构,赤道带6—6键加成的一个异构体为开环结构;S原子加成在4种6—5键上均可产生开环和闭环两种稳定构型.加成在6—5双键的异构体其闭环构型更稳定,加成在6—5单键的异构体其开环构型更稳定.闭环异构体中S原子加成在碳球极处6—6键上的构型1,2最稳定,开环异构体中S原子加成在赤道带6—6键上的构型8最稳定.

The structures and stability of 12 possible isomers of the fullerene derivatives of C70S were studied by using semiempirical AM1, PM3 and MNDO methods. The calculation results indicate that there are three 6-6 closed and one 6-6 opened isomers which S atom is added to unequatioria 6-6 bonds respectively, meanwhile, each of four 6-5 adducts has both closed and opened structures in which one 6-5 closed and three 6-5 opened structures are more stable when the S atom is added to one 6-5 double bond and three 6-5 single bonds respectively. Among all the closed isomers, the structure of C70S in which the S atom is added to the 6-6 bonds at the pole of C70 is the most stable. The open structure while S atom is added to equatoria 6-6 bonds is more stable than other opened isomers.