Kinetic and Mechanistic Studies of Highly Reactive Species Containing Electron-Deficient Main Group Atoms, and the Synthesis of Novel Molecules

本项目的目标是了解控制13、14和15族的第二、第三和第四行元素的缺电子和多键物种的反应的因素。将探索二甲基二硅炔(MeSiSiMe)的生成，以解决包含硅-硅三键的分子的结构和反应活性，目前尚不清楚。一类新型的缺电子物种，在反应原子上含有四个价电子，既带电(如BrC：+和Ph-Si：+)，又带电(Ph-B：和Ph-Al：)，能够以协调或逐步的方式形成三个新的键。反应性锡烯的新前体(R2锡：)将允许探索含二价锡原子的中性分子的全部反应范围，而不存在空间屏蔽取代基。空间无阻碍的硫代硅烯R(Li)Si：将用于探索三重态硅烯的化学，并将启动一个新的计划来设计和构建“分子支架”，这是一种刚性支架，能够对安装在颌骨之间的二价物种施加预先选择的大键角。这将允许研究处于不寻常电子态的分子的光谱和化学，如三重态硅烯。活性碳基中间体的研究揭示了有机反应发生的基本机制，为控制有机反应活性提供了基本的理解和预测工具。在有机化学和高分子化学项目的支持下，华盛顿大学化学系的彼得·P·加斯帕教授正在研究基于碳基中较重的元素-硅、锗和锡-的类似物种的制备和反应活性。这些研究将使有机化学中强大的机械论思想扩展到整个元素周期表中成键和断键过程的预测和合理化，此外，还将为控制化学气相沉积硅膜反应的因素提供预测性的见解，这些反应构成了许多现代半导体工业的基础。

The goal of this project is to understand the factors that control the reactions of electron-deficient and multiply bonded species containing second-, third- and fourth-row elements of groups 13, 14, and 15. The generation of dimethyldisilyne (MeSiSiMe) will be explored in order to address the structure and reactivity of molecules containing the silicon-silicon triple bond, as yet unknown. A novel class of electron-deficient species containing four valence electrons at the reactive atom, both charged (e.g. Br-C:+ and Ph-Si:+) and neutral (Ph-B: and Ph-Al:), offer the capability of forming three new bonds in either a concerted or stepwise manner. New precursors for reactive stannylenes (R2Sn:) will allow the exploration of the full range of reactions available to neutral molecules containing divalent tin atoms, without the presence of sterically shielding substituents. Sterically unencumbered lithiosilylenes R(Li)Si: will be used for the exploration of the chemistry of triplet silylenes, and a new program will be initiated for the design and construction of "molecular vices" that are rigid scaffolds capable of imposing preselected large bond angles on divalent species mounted between the jaws. This will allow the study of the spectroscopy and chemistry of molecules in unusual electronic states like triplet silylenes.The study of reactive carbon-based intermediates has shed light on the fundamental mechanisms by which organic reactions occur, providing both basic understanding and predictive tools for the control of organic reactivity. With the support of the Organic and Macromolecular Chemistry Program, Professor Peter P. Gaspar, of the Department of Chemistry at Washington University, is studying the preparation and reactivity of analogous species based on the heavier elements in the carbon group - silicon, germanium, and tin. These studies will lead to the extension of the powerful mechanistic ideas of organic chemistry to the prediction and rationalization of bond-making and bond-breaking processes throughout the periodic table, and in addition will provide predictive insights into the factors controlling the reactions involved in the chemical vapor deposition of silicon films that form the basis of much of the modern semiconductor industry.