NMR and IR Studies of Activation of Small Molecules by Organometallic Complexes

大多数化学反应都经历了一系列的阶段，有的快，有的慢。在途中，经常会有高活性的物种，在室温下可能会持续一小部分秒。这些物种的性质和反应性往往是决定化学反应最终结果的关键。此外，这些生命短暂的物种本身就是具有根本意义的分子，通常无法用传统技术进行研究。光化学反应可以在低温下发生，并可以由激光引发，这为生成高活性络合物提供了一种非常方便的方法。在这项提案中，我们将开发一种结合先进光谱技术的新方法。我们将在低温下用激光在最先进的核磁共振(核磁共振)光谱仪的探头内照射样品，这样我们就可以确定新的反应分子结构。为了实现这一目标，我们要求我们的新络合物稳定几秒钟，我们将使用快速红外光谱测量来确定允许这些测量的最佳条件。这种技术的结合以一种前所未有的方式利用了最新的仪器。我们的化学目标将是：(A)金属与二氧化碳的络合物，这是了解如何减少温室气体的重要中间体；(B)碳氢化合物与金属的络合物，这是了解如何将甲烷催化转化为有价值的产品的重要中间体；(C)简单的硅和氮化合物在过渡金属上的反应，集中在氢的键被打破的过程中，因为它们在催化中的重要性；(D)过渡金属与惰性气体氙气的络合物，因为这种不活泼的气体具有基本的重要性。

Most chemical reactions proceed through a series of stages, some fast and some slow. En route, there are often highly reactive species that may last a small fraction of a second at room temperature. The nature and reactivity of these species is often key to determining the final outcome of the chemical reaction. Furthermore, these short-lived species are molecules of fundamental interest in their own right which often cannot be studied by conventional techniques. Photochemical reactions can occur at low temperatures and can be initiated by lasers and this provides a very convenient method for generating highly reactive complexes. In this proposal, we will develop a new approach combining advanced spectroscopic techniques. We will irradiate samples with a laser inside the probe of a state-of-the-art nuclear magnetic resonance (NMR) spectrometer at low temperatures, so allowing us to determine the structures of new reactive molecules. In order to achieve this, we require our new complexes to be stable for a few seconds and we will use fast infrared spectroscopic measurements in order to determine the best conditions to allow these measurements. This combination of technologies exploits the latest instrumentation in a way that has never been done before. Our chemical targets will be (a) complexes of metals with carbon dioxide, important intermediates for understanding how to mitigate greenhouse gases, (b) complexes of hydrocarbons with metals, important intermediates for understanding how to convert methane to valuable products catalytically, (c) reactions of simple silicon and nitrogen compounds at transition metals, concentrating on processes in which bonds to hydrogen are broken because of their importance in catalysis; (d) complexes of transition metals with the noble gas, xenon, because of the fundamental importance of this unreactive gas.