Experimental Determination and Mechanistic Implications of the Thermochemistry of Singlet Carbenes

这项有机和大分子化学基金资助了哈佛大学Peter Chen博士的研究工作。这项工作的重点是使用激光技术来确定化学键的强度和一些重要分子的稳定性。具体来说，这项工作将(1)开发和利用气相激光光谱技术来测定大中型多原子分子和反应中间体的键强度、形成热和激发态能；(2)测定杂原子取代烯烃的C=C均溶键离解能；(3)直接应用热化学数据，验证了Simons和Goddard提出的烯烃与一对碳烯的均解键能与这些碳烯的单重态-三重态间隙之间的关系。(4)确定评估噻唑盐催化反应中富电子烯烃/亲核碳平衡重要性所需的关键热化学量。

This grant in Organic and Macromolecular Chemistry provides support for the research work of Dr. Peter Chen, Harvard University. This work focuses on using laser techniques to determine both the strengths of chemical bonds and stabilities of a number of important molecules. Specifically, this work will (1) develop and exploit gas-phase laser spectroscopic techniques for determination of bond strengths, heats of formation, and excited-state energies for medium-to-large polyatomic molecules and reactive intermediates, (2) determine the C=C homolytic bond dissociation energy of heteroatom-substituted olefins, and singlet-triplet gaps for the corresponding singlet ground-state nucleophilic carbenes, (3) test the relationship proposed by Simons and Goddard between the homolytic bond dissociation energy of an olefin to a pair of carbenes and the singlet-triplet gap in those carbenes by direct application of thermochemical data, and (4) determine key thermochemical quantities necessary to assess the importance of an electron-rich olefin/nucleophilic carbene equilibrium in reactions catalyzed by thiazolium salts.