Stabilization of encounter complexes of intermolecular frustrated Lewis pairs by dispersion energy donors

分散相互作用现在已经在化学研究的所有领域中被确定，从而产生不寻常的物理性质、构象、反应的选择性和过度拥挤分子的稳定性。最吸引人的方面之一是，以分散能供体形式存在的空间体积也可以导致分子的热力学稳定，从而导致壮观的成键情况或极短的分子间距离。本研究项目的重点是利用分散能供体稳定分子间受阻刘易斯对的相遇复合物。磷、氮和硼衍生的刘易斯碱和刘易斯酸的三芳基衍生物将在芳环的3和5位上配备分散能供体。刚性烷基片段如甲基、异丙基和叔丁基将提供必要的分散能以稳定刘易斯酸和刘易斯碱的相应相遇络合物。总的来说，54个组合的色散能量稳定的遭遇配合物，这将是由核Overhauser增强NMR光谱方法进行研究。相应的分子间相互作用的方向性将进行分析，提供解决方案的结构阐述。此外，将在不同温度下确定缔合常数，从而能够确定热力学参数。此外，氢裂解中受抑的刘易斯对的活性将被研究，从而将遭遇络合物的分散稳定化与催化活性联系起来。实验数据对色散相互作用的量子力学描述具有重要价值，可提高色散校正密度泛函理论的精度。我们的合成研究将通过与S。格里姆。刘易斯酸和刘易斯碱中的每一种的结构将通过基于DFT的方法进行优化，并且随后的能量分解分析将指定各种能量贡献的作用。最终，这提供了一个定性和定量的分析相互作用的色散能量捐助者在一个高度系统的水平。总之，这种刘易斯对的色散能量供体稳定的相遇复合物的方法与SPP 1807的所有关键主题密切相关：- 新型分散能给体的合成-稳定化的结构-与分子间络合有关的分散能给体的定量评价，- 分散能供体稳定化结构的溶剂依赖性和-通过分散能供体的过渡态稳定化

Dispersion interactions have now been identified in all fields of chemical research giving rise to unusual physical properties, conformations, selectivity of reactions and stabilization of overcrowded molecules. One of the most fascinating aspects is that steric bulk in the form of dispersion energy donors can also lead to the thermodynamic stabilization of molecules resulting in spectacular bonding situations or in extremely short intermolecular distances.This research project focusses on the exploitation of dispersion energy donors for the stabilization of the encounter complexes of intermolecular frustrated Lewis pairs. The triaryl derivatives of phosphorus, nitrogen and boron derived Lewis bases and Lewis acids will be equipped in 3 and 5 position of the aromatic rings with dispersion energy donors. Rigid alkyl fragments such as methyl, isopropyl and tertbutyl will provide the necessary dispersion energy to stabilize the corresponding encounter complex of the Lewis acid and Lewis base. All in all, 54 combinations of dispersion energy stabilized encounter complexes are available, which will be investigated by nuclear-Overhauser enhanced NMR spectroscopic methods. The directionality of the corresponding intermolecular interactions will be analyzed offering the elaboration of solution structures. Furthermore, the association constants will be determined at different temperatures enabling for the determination of the thermodynamic parameters. Furthermore, the activity of the frustrated Lewis pairs in the hydrogen splitting will be investigated connecting dispersion stabilization of the encounter complexes to catalytic activity. The experimental data is of high value for the quantum mechanical description of dispersion interactions offering the improvement of accuracy of dispersion-corrected density functional theory. Our synthetic investigations will be complemented by quantum-mechanical calculations in strong collaboration with S. Grimme. The structure of each of the Lewis acid and Lewis base will be optimized by DFT-based methods and subsequent energy decomposition analysis will specify the role of the various energy contributions. Ultimately, this provides a qualitative and quantitative analysis of interacting dispersion energy donors on a highly systematic level. In summary, this approach to dispersion energy donor-stabilized encounter complexes of Lewis pairs strongly connects to all of the key-topics of the SPP 1807: - synthesis of novel dispersion energy donor -stabilized structure- quantitative evaluation of dispersion energy donors in connection with intermolecular complexation,- solvent dependency of dispersion energy donor-stabilized structures and- transition-state stabilization through dispersion energy donors