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

现代分子化学的一条主要发展路线是提供能够选择性地激活惰性小分子(如二氢、氮或二氧化碳)的化合物，但也能够在更复杂的分子中提供单独的、非常强的键(例如，C-F或C-H键)用于化学过程。理想情况下，这种活化是在热力学条件下进行的，这允许在催化过程中整合活化步骤。过渡金属络合物为这一目的提供了理想的电子条件，因为中心金属的配位和氧化态的改变很容易实现。许多过渡金属的缺点是它们的可获得性有限，在某些情况下还具有毒性。因此，使用丰富的、对生理无害的主族元素，如硅、硼或铝来进行这种键活化过程是绝对可取的。在过去的十年里，出现了几类主族元素化合物，它们能够提供基本的化学键活化过程，如氧化加成和还原消除(金属咪酯)。它们是：卡宾的类似物，杂烯和空间受阻的路易斯酸和碱的组合，受挫的刘易斯对。特别是在卡宾类似物和杂烯的情况下，这些过程有时具有显著的热力学驱动力或开辟了新的、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，需要对主要族元素化合物进行有针对性的修饰。在我们提出的项目中，我们展示了从杂环戊二烯和容易获得的主族元素二氯化物合成一系列极性杂烯和双环卡宾类似物的机会。这两类物质由于其特殊的成键情况而具有新的性质，这将在本项目中进行探索。调查将集中在新化合物的可获得性和稳定性的基本问题上。此外，还将进行反应性研究，以评估它们在键活化反应中的潜力。在拟议的项目成功后，我们将获得两类新的主族元素化合物，它们原则上能够起到金属硫化物的作用。拟议的研究集中在这些新化合物的合成、拓扑结构和电子结构上，并将首次表明它们的反应活性。

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.