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采用密度泛函理论方法在B3LYP/6-311G(d,p)水平上对527个多氯代菲分子的几何结构进行了全优化并计算得到它们的热力学性质(等容热容(Cv)、熵(S)、标准生成焓(ΔfH)和标准生成Gibbs自由能(ΔfG)),研究了这些性质与取代的氯原子数目和位置的关系,根据各异构体的相对标准生成Gibbs自由能(Δr,fG)的大小,得到它们的热力学稳定性顺序.计算结果表明:绝大多数多氯代菲分子具有非平面的几何构型,在多氯代菲分子中存在三种类型的分子内弱相互作用(H…H、C—H…Cl和Cl…Cl相互作用),随着分子中取代的氯原子数目的增加,多氯代菲最稳定异构体的ΔfH和ΔfG开始时逐渐减小,然后又快速增加.具有相同数目氯原子的多氯代菲异构体的ΔfH和ΔfG与氯原子的取代位置有很大的关系.多氯代菲异构体的相对热力学稳定性主要由分子内的离域π键和Cl…Cl核排斥作用的强弱决定.
The geometrical structures of 527 polychlorinated phenanthrene molecules at the B3LYP / 6-311G (d, p) level were fully optimized by density functional theory and their thermodynamic properties (Cv) were calculated. , The entropy (S), the standard enthalpy of formation (ΔfH) and the standard Gibbs free energy (ΔfG)), the relationship between these properties and the number and position of substituted chlorine atoms was studied and the relative standard of each isomer was generated Gibbs free energies (Δr, fG) are obtained, and their order of thermodynamic stability is obtained.The calculation results show that most of the polychlorinated phenanthrene molecules have non-planar geometry, and there are three kinds of polychlorinated phenanthrene molecules Type of intramolecular weak interaction (H ... H, C-H ... Cl and Cl ... Cl interaction), as the number of chlorine atoms in the molecule increases, the most stable isomers of polychlorinated phenanthrene ΔfH and ΔfG decreases initially and then rapidly increases ΔfH and ΔfG of polychlorinated phenanthrene isomers with the same number of chlorine atoms have a strong relationship with the substitution position of chlorine atoms The relative thermodynamic stability of the bulk is dominated by the intramolecular delocalization π bond and Cl ... Cl core repulsion Weak decision.