Abstract

The problem of the unit slope of the Brønsted plot for the proton transfer reaction from the “hard” CH-acids is considered by the example of a series of gas-phase deprotonation reactions of substituted benzenes with the CH₂CN^– anion. The discussion is conducted within the framework of the theory of non-equilibrium reactions. The use of intramolecular reorganization (IMR) method allows calculate directly the structure and energy of the activated complex. A comparison is made of two models. In model 1, as with the standard approach, proton tunnelling process is associated with the system potential V(r) (r is proton coordinate), whereas in model 2, it is associated with the potential of reaction zone X (including the breaking (A‒H) and formed (H‒B) bonds), V_X(r). The V_X energy has been calculated using the Mayer’s APOST program, designed to calculate the mono- and diatomic components of the system energy. The accepted level of calculation of the energies V and V_X (HF/6-31G**//HF/3-21G**) has been determined by APOST program capabilities. Key feature of model 2 is almost complete insensitivity of the proton tunneling frequency, ν_t, to changes of reaction energy ΔE₀₀. The end result is an increase of the Brønsted coefficient α from 0.67 (for model 1) to 0.83. It is shown that when going from the gas phase to the solution (reaction in DMSO medium), α value increases to 0.97.

中文翻译：

---

非平衡法框架下的布朗斯台德关系分析。苯与CH 2 CN-阴离子的气相反应

摘要

所述布朗斯台德情节用于从“硬” CH-酸的质子转移反应的单位斜率的问题是由一系列取代的苯与CH的气相去质子化反应的例子考虑₂ CN ^-的阴离子。讨论是在非平衡反应理论的框架内进行的。分子内重组（IMR）方法的使用允许直接计算活化复合物的结构和能量。比较两个模型。在模型1中，与标准方法一样，质子隧穿过程与系统电势V（r）相关（r是质子坐标），而在模型2中，其与反应区电势相关X（包括断裂（A‒H）和已形成的（H‒B）键），V _X（r）。的V _X能量一直使用Mayer氏APOST方案，设计成计算系统的能量的单-和双原子分量计算。能量V和V _X（HF / 6-31G ** // HF / 3-21G **）的可接受的计算水平已由APOST程序功能确定。模型2的关键特征是质子隧道频率几乎完全不敏感，ν_吨，反应能量的变化Δ ë ₀₀。最终结果是布朗斯台德系数α从0.67（对于模型1）增加到0.83。结果表明，当从气相到溶液（在DMSO介质中反应）时，α值增加到0.97。