氧原子与二硫化碳反应的机理

用从头计算法、内禀反应坐标和电子密度拓扑分析方法研究了3P态氧原子与二硫化碳的反应.找到了分别形成CS SO,S OCS和S2 CO三个反应通道上的极小点和过渡态.采用UHF/631G进行几何构型优化,并在UMP2/631G水平上进行能量校正.三个反应通道上的稳定点和过渡态都经内禀反应坐标(IRC)跟踪得以确认,并用电子密度拓扑分析方法考察了反应过程中化学键的变化.计算结果表明,反应过程中所有稳定点和过渡态都具有Cs对称性,即对每个反应通道而言在整个反应过程中分子始终保持在同一平面内.在三个反应通道中,第一个反应通道O CS2→CS SO由于具有较小的活化能而更容易发生,与实验结果相一致.文中对反应机理进行了较详细的讨论.

Theoretical Studies on the Reaction of Atomic O (3P) with CS2

Ab initio calculation, intrinsic reaction coordinate (IRC) tracing and topological analysis of electron density have been carried out for the reaction of atomic O(3P)with CS2. Minima and saddle points leading to the formation of CS+SO, S+OCS and S2+CO were found. Stationary points were located at the UHF/6 31G*level and the energies were corrected at the UMP2/6 31G*level. Stationary points on each one of the three reaction channels were confirmed by the IRC tracing. Topological analysis of electron density was employed for investigating the changes of chemical bonds in the reaction process. The calculated result reveals that all minima and transition states have Cs symmetry, i.e., the Cs symmetry is maintained on the whole pathway for every reaction channel. The reaction channel (1), O+CS2→CS+SO, is easier to be achieved than the other two because of its low energy barrier. It is in agreement with the experimental observations. The detailed information for the reaction mechanism has been discussed.