Hydrogen complexation and activation in metal-free systems

无金属体系中的氢络合和活化

• 批准号: 153089062
• 负责人: Professor Dr. Wolfram Sander
• 金额: --
• 依托单位: Organische Chemie II - Physikalisch-Organische Chemie (AG Sander)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/153089062?language=en
• 关键词: Hydrogen; complexation; activation; metal; free

Matrix isolation spectroscopy has been used to investigate the interactions and reactions of a variety of FLPs, metal complexes, carbenes, and model compounds with molecular hydrogen. Our experimental set-up allows us to isolate these systems in solid hydrogen as well as H2-doped argon at temperatures ranging from 3 – 30 K. A draw-back was the observation that all FLPs investigated are of low volatility and at the same time thermally labile. Thus, a direct sublimation was not possible. However, the dihydrogenated FLP are less polar and more volatile and can be sublimed. In the gas phase H2 is eliminated and the FLPs can now be deposited in matrices. This is a mechanistic important result since it demonstrates the reversibility of the H2 addition in the gas phase.From that observation, a procedure was developed for the matrix-isolation of FLP 6a and similar FLPs. The FLPs were spectroscopically characterized and reactions with H2 and CO investigated. Both H2 and CO form complexes with the FLPs.An interesting system that inserts into H2 even at cryogenic temperatures is azulenylcarbene 11. This is only the second singlet carbene known to insert into hydrogen at cryogenic temperatures. A very strong kinetic isotope effect suggests that quantum chemical tunneling is involved in the insertion reaction. Since tunneling is a very basic phenomenon that might play a role in many reactions involving H2, we plan to explore this system in great detail.

基质隔离光谱已被用来研究各种荧光素、金属络合物、卡宾和模型化合物与分子氢的相互作用和反应。我们的实验装置允许我们在3-30K的温度范围内将这些系统隔离在固体氢以及掺氢的Ar中。回溯是观察到所有研究的FLP都具有低挥发性，同时热不稳定。因此，直接升华是不可能的。然而，二氢FLP的极性较小，挥发性更强，可以升华。在气相中，H2被消除，FLP现在可以沉积在基质中。这是一个重要的力学结果，因为它证明了气相中H2加成的可逆性。根据这一观察，开发了一种用于FLP 6a和类似FLP的基质分离的程序。对其进行了光谱表征，并研究了它们与氢气和一氧化碳的反应。H2和CO都与FLPS形成络合物。一个有趣的体系，即使在低温下也能插入到H2中，这是已知的第二个在低温下插入到氢中的单线态卡宾。很强的动力学同位素效应表明，量子化学隧穿参与了插入反应。由于隧穿是一种非常基本的现象，可能会在涉及氢的许多反应中发挥作用，因此我们计划非常详细地探索这个系统。