C_(72)衍生物C_(72)X_4(X=H,F,Cl)的理论研究

Theoretical study on fullerene C_(72)'s derivatives C_(72)X_4(X=H,F,Cl)

在混合密度泛函B3LYP理论下,用6-31G*基函数对富勒烯C72及其衍生物C72X4(X=H,F,Cl)进行了几何构型优化。计算了分子静电势、前线轨道能级差、反应能、核独立化学位移(NICS)和振动频率。计算结果表明,C72(#11188)球外负静电势出现在一对相邻五边形公共顶点以及两个六边形-五边形-六边形公共顶点区域,这些点即为化学反应中最可能的活性点;C72X4均是势能面上的稳定驻点;C72X4的能隙比C72大,这些加成反应都是放热的,并且具有很强的芳香性。因此它们都有可能合成出来。

Stimulated by recent preparation and characterization of the first C72 C14 fullerene derivative with one fused pentagons, the C72 fullerene and its exohedral derivatives C72X4（ X = H, F, C1 ）have been reported here. The molecular electrostatic potential, HO- MO-LUMO gap energies ,reaction energies, nucleus independent chemical shifts（NICS） and harmonic frequencies have been studied with the density functional theory method at the B3LYP/6-31 G＊ level. The calculated results indicate that the negative potential on C72 （#11188 ）outside the sphere is localized in the neighbourhood of the abutting pentagon sites and both the hexagon-pentagon-hexagon vertex fusions. They constitute the most probable active sites in chemical reactions. Three structures are the stationary points on the potential energy surface of C72 X4 molecules, aod the LUMO-HOMO gap energies of C72 X4 are higher than C72 （#11188） and all of these addition reactions are exothetmic. They were highly aronratic. Therefore,it is quite possible to be synthesized experimentally.