Biradical-Like Reactive Intermediates

化学结构、动力学和机理B项目支持科罗拉多大学博尔德分校的Josef Michl教授研究过烷基化低聚硅烷在其最低单线态激发态下以前未知的松弛几何结构，这是这些化合物中观察到的蓝色和绿色排放的原因。这些结构包含一个三角形双锥体的硅原子或两个处于四面体和三角形双锥体中间的硅原子，它们的硅原子携带五个而不是通常的四个“价”轨道。计算出的结构对硅纳米粒子和所有饱和分子中的电子激发和电子传导有影响，但这需要实验验证。第二个独立项目涉及二十面体碳硼烷笼CB11的化学性质。我们建议制备新的负离子/自由基对作为新的空穴导体的组成部分，并研究当它们含有裸硼顶点时这种笼的反应性。拟议中的研究尤其与太阳能电池中的太阳能转换和光子学相关（例如，了解可用于电视和计算机显示器的硅纳米颗粒中的光发射）。迄今为止，一些理论预测尚未得到验证，该奖项的工作将提供急需的实验验证。这项工作将为研究生和博士后研究人员在合成有机和实验物理化学方面提供良好的培训。

The Chemical Structure, Dynamics and Mechanisms B Program in the Division of Chemistry supports Professor Josef Michl of the University of Colorado at Boulder for investigation of previously unknown relaxed geometrical structures of peralkylated oligosilanes in their lowest singlet excited state, which are responsible for observed blue and green emissions in such compounds. These structures contain one silicon atom in a trigonal bipyramidal geometry or two silicon atoms at geometries half-way between tetrahedral and trigonal bipyramidal, and their silicon atoms carry five instead of the usual four "valence" orbitals. The calculated structures have implications for electronic excitation and electron conduction in silicon nanoparticles and all saturated molecules, but this requires experimental verification. A second independent project deals with the chemistry of the icosahedral carborane cage CB11. It is proposed to prepare new reversible anion/radical couples of potential interest as components of new hole conductors, and to examine the reactivity of such cages when they contain a naked boron vertex. The proposed research is especially relevant for solar energy conversion in solar cells and for photonics (for example, understanding light emission in silicon nanoparticles that may be used in television and computer displays). To date, several theoretical predications have yet to be tested, and the work in this award will provide much-needed experimental verification. The work will provide graduate students and postdoctoral research associates with excellent training in both synthetic organic and experimental physical chemistry.