Heterol Dianions of Group 14 Elements as Building Blocks for the Synthesis of Polarized Multiply-Bonded Compounds and Bicyclic Carbene Analogues

现代分子化学发展的一条主线是提供能够选择性活化惰性小分子如二氢、二氮或二氧化碳的化合物，以及用于化学过程的更复杂分子中的单个非常强的键（例如C-F或C-H键）。理想情况下，这种活化在热力学状态下发生，这允许将活化步骤整合到催化过程中。过渡金属络合物为此目的提供了理想的电子条件，因为中心金属的配位以及氧化态的改变容易实现。许多过渡金属的缺点是它们的可用性有限，并且在某些情况下它们具有毒性。因此，绝对需要使用丰富且生理上无害的主族元素如硅、硼或铝用于这种键活化过程。在过去的十年中，出现了几类主族元素化合物，它们能够提供化学键活化的基本过程，如氧化加成和还原消除（metallomimetika）。它们是：卡宾的类似物、杂烯烃和空间位阻刘易斯酸和碱的组合、受阻刘易斯对。特别是在卡宾类似物和杂烯烃的情况下，这些过程有时具有显著的热力学驱动力或开辟新的、不可预见的反应路径。这两个因素阻碍了它们在催化反应中的整合，并需要对主族元素化合物进行有针对性的修饰。在我们提出的项目中，我们展示了由杂环戊二烯和容易获得的主族元素的二氯化物合成一系列极性杂烯烃和双环卡宾类似物的机会。这两类物质由于其特殊的键合情况而具有新的性质，这将在本项目中进行探索。调查将侧重于新化合物的可用性和稳定性的基本问题。此外，还将进行反应性研究，以评估其在键活化反应中的潜力。在所提出的项目的成功，我们将有机会获得两类新的主族元素化合物，这是在原则上能够作为metallomimetika。拟议的研究集中在这些新型化合物的合成和拓扑结构和电子结构，并将允许其反应性的第一个迹象。

A major line of development of modern molecular chemistry is to provide compounds that are able to activate selectively inert, small molecules such as dihydrogen, dinitrogen or carbon dioxide, but also individual, very strong bonds in more complex molecules (e.g. C-F or C-H bonds) for chemical processes. Ideally, this activation takes place in a thermodynamic regime, which allows the integration of the activation step in catalytic processes. Transition metal complexes provide ideal electronic conditions for this purpose, since the change of the coordination as well as of the oxidation state of the central metal is easy to accomplish. The disadvantage of many transition metals is their limited availability and in some cases their toxicity. Therefore, the use of abundant and physiologically harmless main group elements such as Silicon, Boron or Aluminium for such bond activation processes is absolutely desirable. In the last decade, several classes of main group element compounds have emerged, which are able to provide the basic processes of the chemical bond activation such as oxidative addition and reductive elimination (metallomimetika). These are: analogues of carbenes, heteroalkenes and the combination of sterically hindered Lewis acids and bases, frustrated Lewis pairs. Especially in the case of the carbene analogues and the hetero alkenes, these processes sometimes have significant thermodynamic driving forces or open up new, unforeseen reaction paths. Both factors hamper their integration in catalytic reactions and require targeted modifications of the main group element compounds. In our proposed project, we show opportunities to synthesize a series of polar heteroalkenes and of bicyclic carbene analogous from heterocyclopentadienes and easily accessible dichlorides of main group elements. Both substance classes have novel properties due to their special bonding situations, which will be explored in this project. The investigations will focus on fundamental issues of the availability and stability of new compounds. In addition, reactivity studies will be conducted, which allow to evaluate their potential in bond activation reactions. On success of the proposed project we will have access to two classes of novel main group element compounds, which are in principle able to act as metallomimetika. The proposed studies are focused on the synthesis and the topological and electronic structure of these novel compounds and will allow first indications on their reactivity.