摘要
对2,3-二氮杂二环-[2,2,2]-辛-2-烯 (DBO) 与Cl2、Br2和I2 3种卤素分子形成的s型电荷转移复合物进行了不同方法的理论计算。结果表明, MP2方法结合LanL2DZ*基组可以很好地描述DBO与卤素分子间的相互作用。其中, DBO与I2的结合能为33.6 kJ/mol, 与DBO…Br2的结合能接近, 明显大于DBO…Cl2相应的值。几何结构变化以及布居分析均与这一结果吻合。针对DBO的结构, 对DBO与I2间 形成p型电荷转移复合物以及DBO…(I2)2的可能性进行了理论分析和预测。
The charge-transfer complexes (CTCs) of 2,3-diazabicyclo-[2,2,2]oct-2-ene (DBO) with halogens X-2 (X = Cl, Br and I) have been theoretically investigated by using HF, B3LYP and MP2 methods accompanied with the LanL2DZ* basis set. sigma-type CTCs a re considered, showing the interaction between DBO and halogen can be well described by the MP2 approach, whereas the HF method is unsuitable. When taking the ZPE and BSSE effects into account, the binding energy of DBO with I-2 is calculated to be 33.6 kJ/mol, slightly larger than that of complex (DBOBr2)-Br-... but significantly higher than that of (DBOCl2)-Cl-... by as much as 24 kJ/mol. This energetic variation is in accord with the intermolecular distances between DBO and halogen as well as the results of natural population analysis. pi-type CTCs of (DBOI2)-I-... and DBO...(I-2)(2) have also been examined. While the former is predicted to be unstable owing to the mismatching frontier orbitals, and the latter is most likely to exist.
