Femtosecond Studies of Chemical Reaction Dynamics in Liquids

加州大学伯克利分校的Charles Harris在无机、生物无机和有机金属化学项目的支持下，对相当复杂的有机金属反应的动力学（飞秒时间尺度）和内在机制进行了研究。利用飞秒红外光谱与高压技术相结合，揭示了各种复杂化学反应的内在机理。我们将特别注意溶剂分子在这些反应中的作用。最初的兴趣将集中在过渡金属配合物选择性C-H和Si-H键断裂的激活上。各种更复杂的反应，包括炔聚合，也将审查。反应动力学将借助随机动力学模拟来解释。几种理论方法，包括从头计算和密度泛函方法，将应用于中间体的表征。这项研究将溶液相无机反应的内在机理研究的时间范围扩大了几个数量级。其他措施所产生的瞬间反应的细节将被纳入研究范围。在许多科学和技术领域具有中心重要性的反应网络中，这种迄今为止难以达到的化学变化处于临界点。本研究可能具有重要意义的主题的具体例子包括对生物过程机制的研究，如光合作用和呼吸作用，以及对化学工业中至关重要的金属催化聚合的改进。

Charles Harris of the University of California, Berkeley is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for research on the kinetics (at the femto-second time scale) and the intimate mechanisms of rather complex organometallic reactions. Using femtosecond infrared spectroscopy coupled with high pressure techniques, the intimate mechanisms of a variety of complex chemical reactions will be elucidated. Special attention will be paid to the role of solvent molecules in these reactions. Initial interest will be centered on the activation by transition metal complexes of selective C-H and Si-H bond ruptures. A variety of more complex reactions, including alkyne polymerization, will also be examined. Reaction dynamics will be interpreted with the aid of stochastic dynamic simulations. Several theoretical methods, including ab initio calculations and density functional methods, will be applied to characterization of intermediates. This research is extending the time range accessible in the study of the intimate mechanisms of solution-phase inorganic reactions by several orders of magnitude. The details of reactions that are instantaneous by other measures will be brought under examination. Such heretofore inaccessible chemical changes stand at critical points in networks of reactions that are of central importance in many scientific and technological areas. Specific examples of topics where this research may have great importance include studies of the mechanisms of biological processes such as photosynthesis and respiration, and also improvement of metal-catalyzed polymerizations that are of central importance in the chemical industry.