Synthesis and Reactivity of High Nuclearity Silicon Clusters

在本项目中，我们将系统地研究中性和阴离子的氨基和磷基取代的不饱和四元硅环化合物的反应活性，并与中性双环硅(I)环化合物的反应活性进行比较。各个化合物将通过单晶X射线衍射、核磁共振和UV-Vis光谱、质谱学和量子化学计算进行仔细表征，以可视化分子轨道和执行键分析。一个主要目标是阐述这些硅环化合物与小分子的反应性。磷基取代的衍生物有望表现出与相应的氨基取代环化合物显著不同的电子性质，这将通过与小分子如H2、CO、CO2、NH3和乙烯的键激活来探索。新型阴离子硅环化合物由于低配位硅原子具有更多的Lewis碱性配位而被提出以提供更高的反应活性。这将使新类型的反应能够与这些应变的硅环化合物进行。中性的环丁二烯类硅环化合物具有很强的给体和受体位置，将在与一氧化碳、二氧化碳、氨和硼烷等小分子的反应中被利用。此外，还设计了一个阴离子六核分子硅团簇，其中增加了Lewis酸和Lewis碱性中心。将探索该簇合物与亲电性的反应，以系统地比较该簇合物与相应的中性六顶簇的反应性。此外，还尝试了合成具有未取代硅原子和双(硅基)氨基取代基的新型硅簇合物。此外，还将探索将硅环和簇合物包含到具有共轭pi-体系的聚合物中的可能性，并检查它们的光学和电学性质。

In this project, the reactivity of neutral and anionic amido- and phosphido-substituted unsaturated four-membered silicon ring compounds will be systematically investigated and compared with that of a neutral bicyclic silicon(I) ring compound. The respective compounds will be carefully characterized with single crystal X-ray diffraction, NMR and UV-Vis spectroscopy, mass spectrometry and quantum chemical calculations to visualize molecular orbitals and to perform bond analysis. One main objective is to elaborate the reactivity of these silicon ring compounds with small molecules. The phosphido substituted derivatives are expected to exhibit significantly different electronic properties than the respective amido substituted ring compounds which will be explored in bond activations with small molecules such as H2, CO, CO2, NH3 and ethene. The novel anionic silicon ring compounds are proposed to provide enhanced reactivity due to the more Lewis basic coordination sites of the low-coordinate silicon atoms. This will enable new types of reactions to proceed with these strained silicon ring compounds. The neutral cyclobutadiene-type silicon ring compounds feature strong donor and acceptor sites that will be exploited in reactions with small molecules such as carbon monoxide, carbon dioxide, ammonia and borane. Moreover, an anionic hexanuclear molecular silicon cluster with an additional Lewis acidic and Lewis basic site was designed. Reactions of this cluster with electrophiles will be explored to systematically compare the reactivity of this cluster with the corresponding neutral six-vertex cluster. Furthermore, the synthesis of new types of silicon clusters with unsubstituted silicon atoms and bis(silyl)amido substituents is attempted. In addition, the possibility of including the silicon ring and cluster compounds into polymeric compounds with conjugated pi-systems will be explored and their optical and electronic properties will be examined.