论文部分内容阅读
运用ah initio Hartree-Fock从头算,微扰MP2和密度泛函B3LYP方法在不同的基组水平上对碱金属阳离子-苯复合物体系的可能构型进行了自由优化,得到了复合物的能量最低构型为碱金属阳离子位于苯环平面的正上方,频率计算结果表明该结构为稳定结构.复合物的键长、原子净电荷、分子轨道系数、前沿轨道能量、Mullicken键级等都表明,碱金属阳离子和苯环碳原子之间的作用包含p-π作用方式,碱金属阳离子与苯结合时电子从苯环向碱金属阳离子转移,形成电荷转移复合物.它们之间的结合方式和氢键的结合方式相似,但计算得到的热力学参数表明复合物中碱金属阳离子与苯之间的结合强度远远大于典型的氢键,尤其是锂离子-苯复合物的生成焓已和普通的化学键相当.复合物的红外特征振动频率位于200cm~(-1)附近,对应于碱金属阳离子垂直于苯环平面的来回振动,同时形成复合物后,原来位于3200cm~(-1)的苯的C—H振动红外活性消失.
Using ah initio Hartree-Fock ab initio, perturbative MP2 and density functional B3LYP methods, the possible configurations of the alkali metal cation-benzene complex system are optimized at different basic group levels, and the lowest energy of the complex is obtained Configuration of the alkali metal cation is located directly above the benzene ring plane, the frequency calculation results show that the structure is stable structure.The bond length, atomic net charge, molecular orbital coefficient, the frontier orbital energy, Mullicken key grade and so on, The interaction between the metal cation and the benzene ring carbon atom includes the action of p-π. When the alkali metal cation is combined with benzene, the electrons are transferred from the benzene ring to the alkali metal cation to form a charge transfer complex. The calculated thermodynamic parameters show that the bond strength between the alkali metal cation and benzene in the complex is far greater than that of the typical hydrogen bond, and especially the enthalpy of formation of the lithium ion-benzene complex has been equivalent to that of the normal chemical bond The infrared vibrational frequency of the complex is located near 200cm -1, corresponding to the back-and-forth vibration of the alkali metal cation perpendicular to the plane of the benzene ring, C-H infrared activity after vibration was originally located 3200cm ~ (-1) benzene disappears.