CH3SS与OH自由基反应机理的理论研究

应用密度泛函理论(DFT)对CH3SS与OH自由基单重态反应机理进行了研究.在B3PW91/6-311+G(d,p)水平上优化了反应通道上各驻点(反应物、中间体、过渡态和产物)的几何构型,用内禀反应坐标(IRC)计算和频率分析方法对过渡态进行了验证.在QCISD(T)/6-311++G(d,p)水平上计算了各物种的单点能,并对总能量进行了零点能校正.研究结果表明,CH3SS与OH反应为多通道反应,有5条可能的反应通道.反应物首先通过不同的S—O键相互作用形成具有竞争反应机理的中间体IM1和IM2.再经过氢迁移、脱氢和裂解等机理得到主要产物P1(CH2SS+H2O),次要产物P2(CH2S+HSOH),P3(CH3SH+1SO)和P4(CH2SSO+H2),其中最低反应通道的势垒为174.6kJ.mol-1.

Theoretical study on the reaction mechanism of CH3SS with OH radical

B3PW91 method was employed to study the reaction mechanism of CH3SS and OH radicals at 6-311+G(d,p) basis sets.Geometries of the stationary points were completely optimized.The transition states were validated by the vibrational analysis and the internal reaction coordinate(IRC) calculations,which testified the authenticity of intermediates and transition states.More accurate energy information is provided by single-point calculations at QCISD(T)/6-311++G(d,p) method.Five feasible reaction pathways of this reaction have been studied.The results indicate that the associations of CH3SS and OH are barrierless processes.Firstly,it forms the energy-rich adducts IM1 and IM2 through the S—O bonds.The adducts IM1 and IM2 would then dissociate into the main product P1(CH2SS+H2O),as well as the secondary important products P2(CH2S+HSOH),P3(CH3SH+1SO) and P4(CH2SSO+H2) via different channels(hydrogen shift,H2 elimination and dissociations).