Shan Xiao, Sambrook Mark R, Clary David C
Physical and Theoretical Chemistry Laboratory, Department of Chemistry , University of Oxford , South Parks Road , Oxford OX1 3QZ , United Kingdom.
CBR Division, Defence Science and Technology Laboratory (Dstl) , Porton Down , Salisbury SP4 OJQ , United Kingdom.
J Phys Chem A. 2019 Jan 10;123(1):59-72. doi: 10.1021/acs.jpca.8b10416. Epub 2018 Dec 18.
In order to further understand and support approaches for the degradation and destruction of toxic chemicals, the thermal decomposition of the nerve agent VX through possible pericyclic hydrogen transfer reactions is investigated using simulant molecules. A total of four simulant molecules are studied. Three of them have only one possible H-transfer site, while the other has two. They are chosen to bring physical insights into individual steps of the pericyclic reaction mechanism as well as the possible existence of competing mechanisms. The unimolecular reaction rate constants at the high-pressure limit are calculated. Geometries of stationary structures on the potential energy surfaces are calculated with the MP2 method as well as the B3LYP and M06-2X functionals and 6-311++G(d,p), jul-cc-pVTZ, and aug-cc-pVTZ basis sets. The barrier heights are corrected using energy values obtained at the CBS/QB3 level of theory. The contribution of the quantum tunneling effect to the reaction rate constants is included using one-dimensional semiclassical transition state theory. Adiabatic barrier heights, reaction rate constants, and branching ratio of the competing mechanisms are reported.
为了进一步理解和支持有毒化学品的降解与破坏方法，使用模拟分子研究了神经毒剂VX通过可能的周环氢转移反应进行的热分解。总共研究了四个模拟分子。其中三个只有一个可能的氢转移位点，而另一个有两个。选择它们是为了深入了解周环反应机理的各个步骤以及竞争机理的可能存在。计算了高压极限下单分子反应速率常数。使用MP2方法以及B3LYP和M06 - 2X泛函和6 - 311++G(d,p)、jul - cc - pVTZ和aug - cc - pVTZ基组计算了势能面上稳定结构的几何形状。使用在CBS/QB3理论水平获得的能量值校正势垒高度。使用一维半经典过渡态理论计算量子隧穿效应对反应速率常数的贡献。报告了绝热势垒高度、反应速率常数和竞争机理的分支比。
