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

大多数化学反应都经历一系列的阶段，有些快，有些慢。在途中，通常会有高活性物质，在室温下可能持续不到一秒。这些物质的性质和反应性通常是决定化学反应最终结果的关键。此外，这些寿命短的物种本身就是具有根本意义的分子，通常无法通过常规技术进行研究。光化学反应可以在低温下发生，并且可以由激光引发，这为产生高反应性络合物提供了非常方便的方法。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。我们将在低温下用最先进的核磁共振（NMR）光谱仪的探针内的激光照射样品，从而使我们能够确定新反应分子的结构。为了实现这一目标，我们要求我们的新复合物稳定几秒钟，我们将使用快速红外光谱测量，以确定允许这些测量的最佳条件。这种技术组合以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，理解如何减少温室气体的重要中间体，（B）烃与金属的络合物，理解如何催化将甲烷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，由于氢在催化作用中的重要性，集中于氢键断裂的过程;（d）过渡金属与惰性气体氙的络合物，因为这种不起反应的气体至关重要。

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.