Flowing Afterglow - Guided Ion Beam Studies of Reactive Organic Intermediates

对中性有机碎片和离子有机碎片在气相中的形成、热力学稳定性和化学反应活性进行了实验和理论研究。这项研究将测量环丙烷、苯、甲苯和萘等简单有机化合物的顺序碳-碳和碳氢离解能，并表征参与这些分子逐键分解的选定离子片段的气相反应性。流动余辉引导离子束装置将被用来测量选定的卡宾、双自由基、三自由基及其相应负离子的碰撞诱导解离反应的活化能。这些数据将使我们能够研究热化学问题，如化学键中电子促进(杂化)效应的能量后果，自由基和卡宾的固有Bronsted酸，苯和相关芳香族化合物中第一、第二和第三碳氢键解离能的相对大小，以及有机双自由基中通键耦合和自旋极化效应的能量效益。%有机动力学项目的这笔拨款支持普渡大学罗伯特·R·斯奎尔斯教授的继续工作。这项研究将测量一些简单有机分子的顺序碳-碳键和碳氢键解离能，并表征参与这种逐键分解的选定离子片段的气相反应性。这些实验将为以中性和离子碳为中心的活性中间体提供新的热化学数据。对这些数据的分析将允许对化学中的一些重要理论概念进行评估，其中包括分子的化学键和酸性。

A combined experimental and theoretical investigation of the formation, thermodynamic stability, and chemical reactivity of neutral and ionic organic fragments in the gas-phase will be made. This study will measure sequential carbon-carbon and carbon-hydrogen dissociation energies for simple organic compounds such as cyclopropane, benzene, toluene, and naphthalene, and characterize the gas-phase reactivity of selected ionic fragments involved in the bond-by-bond disassembly of these molecules. A flowing afterglow-guided ion beam instrument will be used to measure activation energies for collision-induced dissociation reactions of selected carbynes, biradicals, triradicals, and their corresponding negative ions. These data will allow an examination of thermochemical issues such as the energetic consequences of electronic promotion (hybridization) effects in chemical bonding, the intrinsic Bronsted acidities of radicals and carbenes, the relative magnitudes of the first, second, and third carbon-hydrogen bond dissociation energies in benzene and related aromatic compounds, and the energetic benefit of through-bond coupling and spin polarization effects in organic biradicals. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Robert R. Squires at the Purdue University. This study will measure sequential carbon- carbon and carbon-hydrogen bond dissociation energies of some simple organic molecules and characterize the gas-phase reactivity of selected ionic fragments involved in this bond- by-bond disassembly. These experiments will provide new thermochemical data for neutral and ionic carbon-centered reactive intermediates. Analysis of these data will allow an evaluation of some important theoretical concepts in chemistry, which include chemical bonding and acidity of molecules.