C_(70)SiH_2可能异构体的结构和稳定性的理论研究

THEORETICAL STUDIES ON THE STRUCTURES AND STABILITY OF VARIOUS POSSIBLE ISOMERS OF C_(70 )SiH_2

分别用半经验的 AM1 ,PM3及 MNDO方法研究了富勒烯衍生物 C70 Si H2 的 1 2种可能异构体的结构和稳定性 .计算结果表明 :Si H2 基团加成在 4种 6-6键上的稳定构型中 ,非赤道带加成的三个异构体为闭环结构 ,赤道带加成的一个异构体为开环结构 :Si H2 基团加成在 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单键的异构体使其开环构型更稳定 .闭环异构体中 Si H2 基团加成在碳球极处 6-6键上的构型 1 ,2最稳定 ,开环异构体中 Si H2 基团加成在赤道带 6-6键上的构型

The structures and stability of 12 possible isomers of the fullerene derivatives of C 70 SiH 2 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 SiH 2 group is added to unequatioria and equatioria 6 6 bonds respectively, meanwhile each of four 6 5 adducts has both colsed and opened structures in which one 6 5 closed and three 6 5 opened structures are more stable when the SiH 2 group 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 SiH 2 in which the SiH 2 group is added to the 6 6 bonds at the pole of C 70 is the most stable. The open structure while SiH 2 group is added to the equatoria 6 6 bonds is more stable than other opened isomers.