RUI: Exploring Mechanistic Parameters Regulating Bond-Activation in the State-Specific Reactions of Gas Phase Transition Metal Ions with Halogenated Molecules

在这项由化学系化学结构、动力学和机理计划支持的项目中，阿肯色州中部大学的威廉·泰勒教授和他的本科生研究团队将研究金属离子对卤化分子中sigma键的激活。感兴趣的反应将在气相中使用选定的离子漂移电池反应器进行，该反应器将使用溅射辉光放电源产生基态和激发电子态的过渡金属离子。然后，这些离子将通过四极滤质器进行质量选择，并被引入含有低压氦和感兴趣的中性反应物分子的漂移池中。随后将使用第二个四极杆对反应产物进行分析。该仪器还将用于通过电子态色谱(ESC)表征金属离子的电子态分布。ESC还将用于确定反应产物的状态特异性。中性反应物种将包括各种卤代甲烷(CH3X、CF3X，其中X=氯、溴和碘)、SF5Cl和SF5Br等。这些实验旨在揭示反应结果(例如，卤素或卤化物提取、HX消除)对各种参数的依赖，包括金属物种的电子态以及反应物中性的结构特征。对选定反应的依赖温度的动力学研究将旨在确定可能的过渡态。这些实验工作将得到反应势能面密度泛函计算的补充。过渡金属离子具有破坏西格马键的能力，这一性质在将碳氢化合物转化为其他更有用的化合物时最有用。了解这一过程的机理将有助于设计用于化学合成和石油工业的新的、更好的催化剂。此外，该项目将为本科生提供在一个他们可能不会接触到的领域进行研究的机会。参与这项工作的本科生受益于宝贵的研究经验，这对他们随后的各种职业选择包括研究生/专业课程和与科学有关的工作都有很好的帮助。

In this project supported by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, Professor William Taylor of the University of Central Arkansas and his undergraduate research team will examine the activation of sigma bonds in halogenated molecules by metal ions. The reactions of interest will be carried out in the gas phase using a selected ion drift cell reactor which will generate transition metal ions in both ground and excited electronic states using a sputtering glow discharge source. These ions will then be mass selected via a quadrupole mass filter and introduced into a drift cell containing low pressures of helium and the neutral reactant molecule of interest. Subsequent analysis of reaction products will be carried out using a second quadrupole. This instrument will also be used to characterize the metal ion electronic state distributions via electronic state chromatography (ESC). ESC will also be used to determine the state-specificity of reaction products. Neutral reaction species will include various halogenated methanes (CH3X, CF3X, where X =Cl, Br and I), SF5Cl and SF5Br, and others. The experiments are designed to reveal the dependence of reaction outcome (e.g., halogen or halide abstraction, HX elimination) on various parameters, including the electronic state of the metal species as well as structural characteristics of the reactant neutral. Temperature dependent kinetic studies of selected reactions will be aimed at identifying likely transition states. These experimental efforts will be complemented by ensity functional calculations of reaction potential energy surfaces. Transition metal ions have the ability to break sigma bonds, and this property is most useful in converting hydrocarbons to other, more useful compounds. Understanding the mechanism of this process will allow design of new and better catalysts for use in chemical synthesis and the petroleum industry. In addition, the project will provide research opportunities to undergraduates in an area which they might not otherwise be exposed to. Undergraduates participating in this work benefit from a valuable research experience which serves them well in a variety of subsequent career choices including graduate/professional programs and science-related jobs.