Frustrated Lewis-Pairs with Silicon, Germanium and Tin as Lewis-acidic Functions

受挫Lewis酸碱对(FLP)的概念是基于Lewis酸和碱之间的相互作用，它们被阻止形成经典的加合物。由此产生的未熄灭的反应势可用于结合、裂解或激活小分子，例如用于氢的异解裂解或用于二氧化碳和其他温室气体的活化。通过这种方式，新的反应和催化过程成为可能。大多数已知的FLP化学是基于元素硼和磷，即作为酸和碱的硼烷和磷烷。其他元素[酸：铝、锌、磷(V)、硅+、碱：氮、氧]的研究要少得多。随着第一个不带电荷的分子内硅磷化合物(C2F5)3SiCH2P(t-Bu)2的问世，我们最近能够成功地将我们在宝石施主-受体化合物领域的长期专业知识应用到FLP化学的现代发展中。由于其巨大的工业重要性，硅的分子化学很容易获得；我们现在希望利用这一优势来进行FLP化学。为此，本项目旨在产生新型分子内FLP体系(Rf)3SiCH2P(R)2，其中Rf表示电负性(例如，氟化)烷基或芳基(z.B.C6F5，C5NF4等)。R代表烷基或胺功能(t-Bu、CH(SiMe3)2、NR‘2等)。硅和磷原子之间的链的长度和类型将是不同的。除硅外，根据HSAB的概念，锗和锡将被用来提供更软的结合伙伴，以激活小分子，因此小分子的结合更弱，因此在催化过程中更容易移除。开发中性Si-FLP系统的概念将在一个并行子项目中转移到具有分离的酸和碱分子的分子间系统。酸是(Rf)4Si等化合物，碱还包括亚磷酸等超碱性体系。最终得到的FLP系统将测试它们结合、激活小分子的活性以及它们的催化能力(例如，不饱和底物的氢化)。对氢的实验将有助于获得机械方面的见解。高级结构研究包括自由分子几何结构的气相电子衍射测量和实验电荷密度研究，以更详细地揭示成键情况。

The concept of frustrated Lewis acid base pairs (FLP) is based on the interaction between Lewis acids and bases, which are prevented from the formation of a classical adduct. The resulting unquenched reaction potential can be used to bind small molecules, cleave or activate them, e.g. for the heterolytic cleavage of hydrogen or for the activation of carbon dioxide and other greenhouse gases. In this way novel reactions and catalytic processes have become possible. Most of the known FLP chemistry is based on the elements boron and phosphorus, i.e. boranes and phosphanes as acids and bases. Other elements [acids: Al, Zn, P (V), Si+, bases: N, O] are much less explored. With the presentation of a first uncharged intramolecular silicon-phosphorus FLP, (C2F5)3SiCH2P(t-Bu)2, we were recently able to apply our long-standing expertise in the field of geminal donor-acceptor compounds successfully to the modern developments of FLP chemistry. The molecular chemistry of silicon is easily accessible because of its immense industrial importance; we now want to make use of this advantage for FLP chemistry.For this purpose, this project aims at generating novel intramolecular FLP systems of the type (RF)3SiCH2P(R)2, with RF representing electronegative (e. g. fluorinated) alkyl or aryl groups (z. B. C6F5, C5NF4, etc.) and R representing alkyl or amine functions (t-Bu, CH(SiMe3)2, NR'2, etc.). The length and type of the chain between the Si and P atoms will be varied. In addition to silicon germanium and tin will be used to offer softer binding partners in terms of the HSAB concept for the activation of small molecules that are thus bound more weakly and hence in terms of catalytic processes more easily removable. The concept to develop neutral Si-FLP systems will be transferred in a parallel subproject to intermolecular systems with separate acid and base molecules. The acids are compounds such as (RF)4Si, and the bases also include super basic systems such as phosphatranes. The resulting FLP systems will be tested for their activity of binding, activating small molecules and for their catalytic ability (e.g. hydrogenation of unsaturated substrates). Experiments with para-hydrogen will contribute the mechanistic insights. Advanced structural investigations include gas phase electron diffraction measurements for free molecule geometries and experimental charge density studies to shed more light on the bonding situation in more detail.