Electron rich and geometrical constrained substituents in molecular silicon compounds - planar(ized) SiIV for bond activation and optoelectronic materials

用于光电应用的均相催化剂和材料已经被积极研究了几十年-其中过渡金属络合物是人们感兴趣的焦点。然而，通过丰富的主族元素化合物来替代通常有毒、难以分离和稀有的过渡金属是期望的。此外，主族化合物在不寻常的键情况下的反应性是基础研究中的主要当前兴趣。本文给出的方法涉及合成和研究的硅（IV）化合物配备丰富的电子和几何约束的取代基。所提出的多齿或大环酰胺基/酚基/吡咯取代基的性质给出了一系列基本问题以及应用问题的答案。（Pro）手性取代基将允许阐明四价硅（IV）的平面反转-这是理论上长期已知的，但实验上被忽视的这类物质的立体动力学方面。取代基的几何畸变导致增强的反应性：路易斯酸性大幅增加，而富电子取代基的亲核性仍然很高。小HOMO-LUMO间隙的结果，导致新的反应的可能性，在激活小分子与强σ键。一方面，在氧化还原反应中的取代基的参与结合在硅（IV）的超配位的能力是合理的，导致在硅（IV）的正式氧化加成。或者，所提出的化合物的强两亲性可以引起特定底物的异裂键活化。平面化的概念最终将实现第一个分子，平面，四价硅（IV）物种，具有大量有趣的结构，反应和光学特性。所提出的结构是合成上直接可获得的，并且量子理论考虑揭示了这样的化合物是高度有吸引力的-例如具有比参考刘易斯酸B（C6 F5）3更强的路易斯酸性和相当大的可见光吸收-中性四价硅（IV）化合物的高度不寻常的性质。受体特性和模块化合成提供了供体功能的简单安装，用于创建例如非线性光学效应。所提出的概念允许在硅（IV）-化合物的立体动力学，反应性和光物理的取代基和平面化的影响的综合检查。第一个有希望的结果在给定的目标进行了讨论。

Homogeneous catalysts and materials for optoelectronic applications have been actively investigated for several decades - with transitions metal complexes in the spotlight of interest. However, an alternative for the often toxic, hard to separate and rare transition metals by abundant main group element compounds is desirable. Moreover, the reactivity of main group compounds in unusual bond situations is of major current interest in fundamental research. The herewith given approach deals with the synthesis and investigation of silicon(IV) compounds equipped with electron rich und geometrically constrained substituents. The nature of the proposed polydentate or macrocyclic amido/phenolato/pyrrolo-substituents gives answer to a series of fundamental as well as applied problems. (Pro)chiral substituents will allow for the elucidation of the planar inversion of tetravalent silicon(IV) - a theoretically long known, but experimentally neglected aspect of stereodynamics in this substance class. The geometrical distortion by the substituents leads to augmented reactivity: the Lewis-acidity increases substantially whereas the nucleophilicity of the electron rich substituents remains high. Small HOMO-LUMO gaps are resulting, leading to new reaction possibilities in the activation of small molecules with strong sigma-bonds. On one hand, the participation of the substituents in redox reactions combined with the ability of hypercoordination at silicon(IV) is plausible, leading to formal oxidative additions at silicon(IV). Alternatively, the strong amphiphilic character of the proposed compounds could provoke heterolytic bond activation of specific substrates. The concept of planarization finally will enable the realization of the first molecular, planar, tetravalent silicon(IV) species, with plenty of interesting structural, reactive and optical features. The proposed structures are synthetically straightforward accessible and quantum theoretical considerations reveal such compounds as highly attractive - with e.g. stronger Lewis-acidity than the reference Lewis acid B(C6F5)3 and considerable absorption of visible light - highly unusual properties of neutral, tetravalent silicon(IV) compounds. The acceptor properties and the modular synthesis offers the easy installation of donor functionalities for the creation of e.g. non-linear optical effects. The proposed concept allows for the integrated examination of the influence of substituents and planarization in silicon(IV)-compounds on stereodynamics, reactivity and photo physics. First promising results in relation to the given objectives are shortly discussed.