Biradical-like Reactive Intermediates

在化学系有机动力学项目的支持下，科罗拉多大学博尔德分校的Josef Michl教授和他的合作者将致力于他们传统兴趣领域的两个项目，即光物理和光化学，以及第三个项目，涉及碳硼烷化学领域的活性中间体及其可分离的类似物。第一个项目是关于他们目前正在努力了解低聚硅烷的电子结构，这是典型的Sigma共轭体系，涉及与激发能局域相关的垂直激发态的松弛，并试图发现和指认它们的三重激发态。用时间分辨拉曼光谱研究了激发态单态的几何驰豫。三重态的检测将低聚硅烷光谱学与第二个项目联系起来，该项目利用了当前赠款期间在提高电子能量损失光谱仪灵敏度方面取得的成就。这有望在低聚硅烷、氟碳化合物、各种基质隔离物种和其他样品中检测到自旋禁止跃迁。第三个项目涉及从阴离子二十面体碳硼烷衍生的化合物的化学，HCB11Me11(-)。对于这个研究小组来说，它仍然是相对较新的，并建立在当前赠款期间发现的一种新型活性中间体的基础上。这些是碳正离子同分异构体和硼叶立德HCB11Me11，它们在初步实验中显示出不同寻常的反应性，现在将进行详细研究。全烷基化碳硼烷阴离子和全氟烷基碳硼烷阴离子也将被用作空间大体积保护基团，以稳定包含主族元素的缺电子原子的结构，用于结构和光谱研究以及化学反应活性的检查。CB11Fx(CF3)12-x类型的全氟阴离子将用于稳定高活性阳离子。有机和高分子化学计划支持科罗拉多大学博尔德分校的约瑟夫·米克尔教授的研究，该研究将影响反应中间体化学领域。对这一领域的贡献将通过在合成有机化学、无机化学、物理化学和理论化学领域的科学期刊上的出版物进行交流。预计这项工作将有助于对本科生、研究生和博士后进行一系列跨学科实验和理论方法的教育和培训，这些方法涵盖了从成键理论、光物理、光谱学和光化学到物理、有机和无机以及制备化学等领域。

With the support of the Organic Dynamics Program in the Chemistry Division, Professor Josef Michl of the University of Colorado-Boulder and his collaborators will work on two projects in the area of their traditional interests, photophysics and photochemistry and on a third project that involves reactive intermediates and their isolable analogs in the field of carborane chemistry. The first project is related to their current effort to understand the electronic structure of oligosilanes, prototypical sigma-conjugated systems, and deals with the relaxation of their vertical excited states that are associated with excitation energy localization, and with an attempt to discover and assign their triplet excited states. The geometrical relaxation of the excited singlets will be examined using time-resolved Raman spectroscopy. The detection of the triplet states connects oligosilane spectroscopy to the second project, which takes advantage of the accomplishments attained in the current grant period with respect to improving the sensitivity of an electron energy loss spectrometer. This is expected to permit the detection of spin-forbidden transitions in oligosilanes, but also in fluorocarbons, in various matrix-isolated species, and additional samples. The third project deals with the chemistry of compounds derived from the anionic icosahedral carborane, HCB11Me11(-). It is still relatively new to this research group and builds on the discovery of a new type of reactive intermediates that was made in the current grant period. These are the isomeric carbonium and boronium ylides HCB11Me11, which show unusual reactivity in preliminary experiments and will now be examined in detail. Peralkylated and perfluoroalkylated carborane anions will also be used as sterically bulky protecting groups to stabilize structures containing electron-deficient atoms of main group elements for structural and spectroscopic studies and well as an examination of chemical reactivity. Perfluorinated anions of the type CB11Fx(CF3)12-x will be used for the stabilization of highly reactive cations. The Organic and Macromolecular Chemistry Program supports the research of Professor Josef Michl of the University of Colorado-Boulder that will impact the field of reactive intermediate chemistry. Contributions to this field will be communicated through publications in scientific journals in the areas of synthetic organic, inorganic, physical, and theoretical chemistry. The work is expected to contribute to the education and training of undergraduate, graduate, and postdoctoral students in a range of interdisciplinary experimental and theoretical methods spanning an area from bonding theory, photophysics, spectroscopy, and photochemistry to physical organic and inorganic as well as preparative chemistry.