阳离子-π体系相互作用的理论研究——Ⅱ.铵离子-二苯复合物体系的密度泛函研究  

Theoretical Studies on Cation - n Interactions II . Density - Functional Theory Investigation on the Configurations of and Interactions in Ammonium Cation - Bibenzene Complexes

作　　者：朱维良[1] 蒋华良[1] 谭小健 陈建忠 翟宇峰 顾健德 林茂伟 陈凯先[1] 嵇汝运[1] 曹阳[2] 

机构地区：[1]中国科学院上海药物研究所新药研究国家重点实验室,上海200031 [2]苏州大学化学系,苏州215006

出　　处：《化学学报》1999年第8期852-859,共8页Acta Chimica Sinica

基　　金：国家杰出青年基金(29725203);"863"高科技项目基金(103-13-04-01)资助项目

摘　　要：运用密度泛函B3LYP/6-31G~*方法对铵离子-二苯复合物体系的可能构型进行了结构优化,得到了复合物的能量最低构型为:铵离子位于两个苯环平面之间分别以两个氢原子和苯环作用,频率计算结果表明该构型为稳定结构.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,铵氢原子和与之接近的苯环碳原子之间通过s-π相互作用而实现铵与两个苯环的结合,结合时电子从苯环向铵转移,形成电荷转移复合物.它们之间的结合方式和铵离子-苯复合物及典型氢键的结合方式相似,计算得到的热力学参数证明了这一点.复合物的红外特征振动频率位于230cm^(-1)附近,振动方式为铵平行于苯环平面来回振动.Density - functional theory (DFT) B3LYP/6 - 31G* approach has been employed to calculate the possible configurations of ammonium - bibenzene ( C6H6...NH4+ ...C6H6 ) complex. The calculation results indicate that the most stable structure of the complex is the configuration where the ammonium cation located between two benzenes with two hydrogen atoms pointing to each benzene ring. The calculated IR spectrum shows that the geometry is reasonable. The bond length, total atomic charges, the coefficient of the molecularorbital, frontier orbital energys, and Mullicken bonding population of the complex indicate that the binding between the ammonium and two benzenes involved thes - π interaction between hydrogens of ammonium and the carbon atoms of benzenes near to the hydrogens of ammonium, with electron transfer occured from the two benzene rings to ammonium, forminmg a charge transfer complex. The calculated results also imply that, similar to that of the ammonium cation - benzene complex, the interaction characteristic of the ammonium cation - bibenzene complex is a typical hydrogen bond. The calculated thermodynamic parameters demonstrate this feature. The normal mode analysis of the predicted vibrational frequency shows that the characteristic vibration mode of the complex is located at about 230 cm-1, correspondeding to the back and forth vibration of the ammonium cation paralleled to the bezene rings.

关 键 词：铵离子 苯 相互作用 二苯 复合物 氢键 密度泛函 

分 类 号：O613.61[理学—无机化学] O625.11[理学—化学]