Crisanti Francesco, Montag Michael, Milstein David, Bonin Julien, von Wolff Niklas
Université Paris Cité, Laboratoire d'Electrochimie Moléculaire, CNRS F-75013 Paris France
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science Rehovot 7610001 Israel.
Chem Sci. 2024 Oct 3;15(43):18052-9. doi: 10.1039/d4sc05683c.
A key challenge in green synthesis is the catalytic transformation of renewable substrates at high atom and energy efficiency, with minimal energy input (Δ ≈ 0). Non-thermal pathways, , electrochemical and photochemical, can be used to leverage renewable energy resources to drive chemical processes at well-defined energy input and efficiency. Within this context, photochemical benzene carbonylation to produce benzaldehyde is a particularly interesting, albeit challenging, process that combines unfavorable thermodynamics (Δ° = 1.7 kcal mol) and the breaking of strong C-H bonds (113.5 kcal mol) with full atom efficiency and the use of renewable starting materials. Herein, we present a mechanistic study of photochemical benzene carbonylation catalyzed by a rhodium-based pincer complex that is capable of metal-ligand cooperation. The catalytic cycle, comprising both thermal and non-thermal steps, was probed by NMR spectroscopy, UV-visible spectroscopy and spectrophotochemistry, and density functional theory calculations. This investigation provided us with a detailed understanding of the reaction mechanism, allowing us to unlock the catalytic reactivity of the Rh-pincer complex, which represents the first example of a metal-ligand cooperative system for benzene carbonylation, exhibiting excellent selectivity.
绿色合成中的一个关键挑战是将可再生底物以高原子和能源效率进行催化转化，同时能量输入最小（Δ≈0）。非热途径，即电化学和光化学途径，可用于利用可再生能源来驱动化学过程，实现明确的能量输入和效率。在此背景下，光化学苯羰基化制备苯甲醛是一个特别有趣但具有挑战性的过程，它结合了不利的热力学（Δ° = 1.7千卡/摩尔）和强C-H键（113.5千卡/摩尔）的断裂，同时具有全原子效率并使用可再生起始原料。在此，我们展示了由基于铑的钳形配合物催化的光化学苯羰基化的机理研究，该配合物能够进行金属-配体协同作用。通过核磁共振光谱、紫外-可见光谱和分光化学以及密度泛函理论计算对包括热步骤和非热步骤的催化循环进行了探究。这项研究使我们对反应机理有了详细的了解，从而能够释放铑-钳形配合物的催化活性，这是苯羰基化金属-配体协同体系的首个实例，具有出色的选择性。
