C_(70)PH可能异构体的结构与稳定性的理论研究

分别用半经验的AM1, PM3及MNDO方法研究了富勒烯衍生物C_(70)PH的12种可能异构体的结构和稳定性。计算结果表明: -PH基团加成在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；-PH基团加成在4种6-5键上均可产生开环和闭环2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-PH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-PH基团加成在赤道带6-6键上的构型8最稳定。

Theoretical Studies on the Structures and Stabilities of Various Possible Isomers of C_(70)PH

The structures and stabilities of 12 possible isomers of C_(70)PH were studied by using semi-empirical AM1, PM3 and MNDO methods. The calculation results indicate that there are three 6-6 closed and one 6-6 opened isomers in which -PH group is added to unequatorial and equatorial 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 -PH 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)PH in which the -PH group is added to the 6-6 bonds at the pole of C70 is the most stable. The open structure is more stable than other opened isomers while -PH group is added to the equatorial 6-6 bonds.