摘要
用半经验的AM1和MNDO方法优化了富勒烯C3 6的等电子体C3 4 BN所有可能异构体的构型 ,分析了各异构体相对稳定性与杂原子取代位置间的关系 .另外 ,比较了C3 6碳笼上同位置地取代杂原子形成的C3 4 BN ,C3 4 B2 和C3 4 N2间的电子结构 ,并分析了C3 4 BN最稳定异构体的振动模式 .结果表明以C3 6∶A (D6h)为母体形成的最稳定C3 4 BN异构体对应于碳笼赤道位置六元环中 1,4 取代产物 ,而以C3 6∶B (D2d)为母体形成的最稳定C3 4 BN异构体对应于碳笼近赤道位置的 1,2 取代产物 .C3 4 BN各异构体的稳定性可能主要由体系的共轭性质决定 .前线轨道能级表明B ,N原子取代所得异构体的氧化 -还原活性按以下顺序递增 :C3 4 B2 <C3 4 BN <C3 4 N2 .理论计算所得C3 4 BN最稳定异构体的红外光谱可为实验指认C3 4 BN提供参考 .
The possible stable structures of substituted fullerenes C34BN formed on the initial C-36 cages of D-6h and D-2d symmetries have been systematically investigated at the AM1 and MNDO levels. The relationship between the stabilities of the C34BN isomers and the sites where boron or nitrogen atoms dope at the C-36 cage has been discussed. The results show that for the C-36 cage with D-6h symmetry, the most stable isomer of C34BN derivative is formed by boron and nitrogen atoms doping at the 1,4-sites in the six-membered ring which locates at the equatorial belt of C-36 cage. While for C-36 cage with D-2d symmetry, the most stable isomer of C34BN derivative is formed by boron and nitrogen atoms doping at the sites near equatorial belt of C-36 cage, which corresponds to 1,2-substitution pattern. It seems that the stabilities of C34BN isomers are mainly determined by the conjugate effect of the cage. The activity of the redox of the C34XY (X, Y = B, N) isomers increases in the following order: C34B2 < C-34 BN < C-34 N-2. The calculated infrared spectra of the most stable isomers of C-34 BN may be useful for the experimental assignment.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2002年第11期1915-1922,共8页
Acta Chimica Sinica
基金
国家自然科学基金 (No .2 0 0 73 0 2 2 )资助项目 .
