气相中正丁烯负离子与N_2O反应机理的理论研究

Theoretical Study on the Reaction Mechanism of n-Butene Anion with N_2O in Gas Phase

采用二阶微扰理论(MP2)计算方法,在6-31++G(d,p)的基组下,对气相中正丁烯负离子与N2O反应的微观机理进行了较为系统的理论计算研究,并在相同基组下进一步用QCISD方法在MP2优化的几何构型基础上做了单点能校正.计算结果表明,正丁烯负离子有顺式和反式异构体,它们的伯碳和仲碳都可以与N2O反应,前者的反应有α-H抽提、β-H抽提、基于IM11和氧抽提路径.而α-H抽提为主要反应路径,产物是丙烯基重氮甲基负离子(cis-CH3CHCHCN-N-,trans-CH3CHCHCNN-).后者的反应有甲基H抽提、乙烯基H抽提、基于IM12'和氧抽提路径,其中甲基H抽提为主反应路径,产物是丁二烯负离子,相比之下,在仲碳位置上的反应更有利一些.抽提氧的反应路径也是主反应的竞争路径,其产物应该能被检测到.此外,不管是主反应路径还是次反应路径都是强放热过程.

Using the second-order Mφller-Plesset perturbation theory（MP2） based on 6-31＋＋G（d,p） basis set, the mechanism for the ion-molecule reaction of n-butene anion with nitrous oxide in gas phase has been characterized in detail.The single-point energies have also been refined at the QCISD/6-31＋＋G（d,p） level to get more accurate energies using the MP2/6-31＋＋G（d,p） optimized geometries.As a result, there are cis and trans isomers in n-butene anion, and both the primary carbon and secondary carbon in n-butene anion can react with N2O, the former contains α-H abstraction pathway, β-H abstraction pathway, IM11 based pathway and O-atom abstraction pathway.The α-H abstraction pathway is the main pathway, whose primary products are cis-propenyl-diazomethyl anion, and trans-propenyl-diazomethyl anion.The latter comprises methyl-H abstraction pathway, vinyl-H abstraction pathway, IM12＇ based pathway and O-atom abstraction pathway.The methyl-H abstraction pathway is the main pathway, whose primary product is butadienyl anion.In comparison, the latter reaction is more favorable.The O-atom direct abstraction reaction can also compete with the major reaction pathway.And its products can be detected.Furthermore, all the reactive pathways, regardless of the main or minor ones, are strongly exothermic processes.