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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Computational Study of the Reaction SH+0_2
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Computational Study of the Reaction SH+0_2

机译：SH + 0_2反应的计算研究

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The reaction of SH + 0_2has been characterized using multireference methods, with geometries and vibrationalfrequencies determined at the CASSCF/cc-pVTZ level and single-point energies calculated at the MRCI/aug-cc-pV(Q+d)Z level. The dominant product channels are found to be SO + OH and HSO + O. Whereasthe formation of SO + OH has a barrier of ??81 Id mol~(-1), it is energetically more favorable than the formationof HSO + O, which is barrierless beyond the endothermicity of ??89 kJ mol~(-1)at 0 K. Thus, the reaction SH+ 0_2?úSO + OH is 2 orders of magnitude faster than the reaction SH + 0_úHSO O at room temperature,revealing that the atmospheric oxidation of SH leads directly to the formation of SO + OH with the ratecoefficient of??1.0 x 10~(-2)cm~3mol~(-1)s~(-1). At temperatures above 1000 K, however, the rates of twochannels become comparable. This may be attributed to the entropy effects leading to the higher pre-exponentialfactor for the channel (forming HSO + O) via a more loose transition state than that (forming SO + OH)entailing a four-centered transition state. Whereas the hydrogen abstraction reaction producing S + HO_2isfound to proceed on the quartet surface, the substantial barrier of??165 kJ mol~(-1)means that it occurs as aminor product channel. Finally, the formation of possible products SO_2+ H is prohibited due to the lack ofa transition state for the direct sulfur insertion.
机译：SH + 0_2的反应已使用多参考方法进行了表征，其几何形状和振动频率在CASSCF / cc-pVTZ水平下确定，单点能量在MRCI / aug-cc-pV（Q + d）Z水平下计算。发现主要的产物通道是SO + OH和HSO +O。尽管SO + OH的形成具有≤81Id mol〜（-1）的势垒，但在能量上比HSO + O的形成更有利。在0 K时吸热度为89 kJ mol〜（-1）时，它是无障碍的。因此，在室温下，反应SH + 0_2？SO + OH比反应SH + 0_HSO O快2个数量级，表明SH的大气氧化直接导致SO + OH的形成，速率系数为？1.0×10〜（-2）cm〜3mol〜（-1）s〜（-1）。但是，在高于1000 K的温度下，两个通道的速率变得可比。这可能归因于熵效应导致通道（形成HSO + O）的通道比形成四中心过渡态的熵（形成SO + OH）更宽松，从而导致通道具有更高的指数前因子。虽然发现产生氢的S + HO_2的夺氢反应在四重奏表面进行，但165 kJ mol〜（-1）的基本势垒意味着它作为氨基产物通道发生。最后，由于缺乏直接硫插入的过渡态，禁止了可能的产物SO_2 + H的形成。

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