An investigation of the gas-phase reactions of molecular oxygen with the molecular anions of 17 compounds formed by resonance electron capture was undertaken using a pulsed e-beam high-pressure mass spectrometer. The molecular anions of sulphur hexafluoride, perfluromethylcyclohexane, cis- and trans-perfluorodecalin, m-chloronitrobenzene, o-, m-and p-fluoronitrobenzene and o-, m- and p-dinitrobenzene were found to be unreactive towards oxygen. Those of o- and p-chloronitrobenzene, penta- and perchlorobenzene, perfluorobenzene, and perfluorotoluene were found to react readily with oxygen. The second-order rate constants for these reactions are shown to bear an inverse dependence on temperature. The reactions involving o- and p-chloronitrobenezene and penta-and perchlorobenzene proceed via a branched mechanism by which an ion of the type [M + O − Cl]− and Cl− ion are simultaneously produced. A greater variety of negative ions are formed in the reactions of the molecular anions of perfluorobenzene and perfluorotoluene with oxygen. The electron affinities of pentachlorobenzene (0.7 eV) and perchlorobenzene (1.0 eV) are also reported for the first time.
使用脉冲电子束高压质谱仪研究了分子氧与通过共振电子捕获形成的 17 种化合物的分子阴离子的气相反应。发现
六氟化硫、
全氟甲基环己烷、顺式和反式
全氟萘烷、间
氯硝基苯、邻、间和
对氟硝基苯以及邻、间和
对二硝基苯的分子阴离子与氧不发生反应。人们发现邻
氯硝基苯和对
氯硝基苯、
五氯苯和全
氯苯、
全氟苯和全
氟甲苯很容易与
氧气发生反应。这些反应的二阶速率常数与温度成反比。涉及邻
氯硝基苯和对
氯硝基苯以及
五氯苯和全
氯苯的反应通过支化机理进行,同时产生 [M + O − Cl]− 类型的离子和 Cl− 离子。
全氟苯和全
氟甲苯的分子阴离子与
氧气反应时会形成更多种类的负离子。
五氯苯(0.7 eV)和全
氯苯(1.0 eV)的电子亲和势也是首次报道。