Influence of substituents on cation-π interactions. 3. Absolute binding energies of alkali metal cation-aniline complexes determined by threshold collision-induced dissociation and theoretical studies
Influence of substituents on cation-π interactions. 3. Absolute binding energies of alkali metal cation-aniline complexes determined by threshold collision-induced dissociation and theoretical studies
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DOI：
10.1016/s1387-3806(03)00104-0
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发表时间：
2003-07-01
影响因子：
1.8
通讯作者：
Rodgers, MT
中科院分区：
文献类型：
--
作者：
Amunugama, R;Rodgers, MT
用引导离子束质谱研究了M+（C_6H_5NH_2）（x）与H_2O的阈值碰撞诱导解离。M+包括以下碱金属离子：Li+、Na+、K+、Rb+和Cs+。检查单和双复合物（即，x=1和2）。在所有情况下，观察到的主要和最低能量的解离通道是完整的苯胺配体的吸热损失。连续解离的第二个苯胺配体观察到在升高的能量在双复合物。还观察到配体交换产物M+ β和M+（C6 H5 NH 2）β的少量产生。主要解离通道的横截面阈值被解释为产生0和298 K键解离能（BDEs）（C6 H5 NE 2）（x-1）M+-C6 H5 NH 2，x=1和2，后占多个离子中性碰撞的影响，反应物的动能和内能，和解离寿命。在B3 LYP/6- 31 G * 水平上的密度泛函理论计算被用来确定这些配合物的结构，并提供必要的实验数据的热力学分析的分子常数。采用B 3LYP/6- 31 G * 几何构型，在MP2（full）/6-311+G（2d，2 p）水平上计算了分子的理论结合能.零点能量和基组叠加误差系数也包括在内。理论和实验之间的协议是非常好的，在所有情况下，除了Li+（C6 H4 NH 2）复杂的理论低估了在这个复杂的结合。在M+（C6 H5 NH 2）（x）结合能的趋势解释在不同程度的静电相互作用和配体-配体排斥的配合物。还进行了比较，以先前确定的实验BDE的M+（C6 H6）（x），M+（C6 H5 CH 3）（x），和M+（C6 H5 F）（x），以检查的影响，取代基上的结合，和控制阳离子π相互作用的强度的因素。(C)2003 Elsevier Science B. V.保留所有权利。
Threshold collision-induced dissociation of M+(C6H5NH2)(x) with Xe is studied using guided ion beam mass spectrometry. M+ include the following alkali metal ions: Li+, Na+, K+, Rb+, and Cs+. Both mono- and bis-complexes are examined (i.e., x=1 and 2). In all cases, the primary and lowest energy dissociation channel observed is endothermic loss of an intact aniline ligand. Sequential dissociation of a second aniline ligand is observed at elevated energies in the bis-complexes. Minor production of ligand exchange products, M+Xe and M+(C6H5NH2)Xe, is also observed. The cross-section thresholds for the primary dissociation channel are interpreted to yield 0 and 298 K bond dissociation energies (BDEs) for (C6H5NE2)(x-1)M+-C6H5NH2, x=1 and 2, after accounting for the effects of multiple ion-neutral collisions, the kinetic and internal energies of the reactants, and dissociation lifetimes. Density functional theory calculations at the B3LYP/6-31G* level of theory are used to determine the structures of these complexes and provide molecular constants necessary for the thermodynamic analysis of the experimental data. Theoretical binding energies are determined from single point calculations at the MP2(full)/6-311+G(2d,2p) level using the B 3LYP/6-31G* geometries. Zero point energy and basis set superposition error coffections are also included. The agreement between theory and experiment is very good in all cases except for the Li+(C6H4NH2) complex where theory underestimated the binding in this complex. The trends in M+(C6H5NH2)(x) binding energies are explained in terms of varying magnitudes of electrostatic interactions and ligand-ligand repulsion in the complexes. Comparisons are also made to previously determined experimental BDEs of M+(C6H6)(x), M+(C6H5CH3)(x), and M+(C6H5F)(x) to examine the influence of the substituent on the binding, and the factors that control the strength of cation-pi interactions. (C) 2003 Elsevier Science B.V. All rights reserved.