C_(60)NH5/6,6/6异构体的理论研究

Theoretical Study of C_60NH 5/6, 6/6 Isomers

用半经验的AM1,PM3及ab initio方法对C_(60)NH两种异构体的结构及光谱进行了理论计算.结果表明,具有开环结构的C_(60)NH的5/6异构体稳定性要高于具有闭环结构的6/6异构体.计算了两种异构体开环与闭环过程的反应坐标,发现6/6开环异构体是势能面上的一局部最小点,而5/6闭环异构体不存在.6/6异构体的H可以在两种镜面异构体之间快速翻转,使其核磁共振谱呈现C_(2v)对称性.通过振动分析确认了所优化的构型确实为势能面的能量最低点,并得到了C_(60)NH各异构体的红外光谱.

Semi - empirical and ab initio studies on the structure and spcetra of C60 NH are reported. The Cs (5/6) isomer with annulene structure is more stable than that of Cs (6/6) isomer. The reaction coordinates for the opening and closing of the transannular bond in the 6/6 - closed and 5/6 - open isomers have been calculated. There is a shallow minimum corresponding to a 6/6 - open structure. The H atom of 6/6 isomer can be fast inverted between two mirror isomers so its NMR spectra show C2v symmetry. The vibrational analysis indicates that the optimized geometry is surely the minimum energy point in the potential surface. The IR spectra of C60NH are obtained by calculation.