Bermejo José, Santos Laura L, Álvarez Eleuterio, López-Serrano Joaquín, Suárez Andrés
Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), CSIC and Universidad de Sevilla, Avda Américo Vespucio, 49, Sevilla 41092, Spain.
Instituto de Investigaciones Químicas (IIQ), CSIC and Universidad de Sevilla, Avda Américo Vespucio, 49, Sevilla 41092, Spain.
ACS Catal. 2025 Jun 20;15(13):11530-11543. doi: 10.1021/acscatal.5c02021. eCollection 2025 Jul 4.
Air-stable ruthenium-(II) complexes based on a picoline-derived CNC pincer ligand, [RuH-(CNC)-(CO)] ( = PPh, = Br; = CO, = BF), were found to catalyze under basic conditions the oxidation with NO of a series of alcohols to carboxylates. Both [RuH-(CNC)-(CO)] complexes react readily with strong bases (BuOK or KHMDS), giving rise to a Ru-(II) complex containing a deprotonated CNC* ligand (when = PPh) or a Ru(0)-CNC derivative (for = CO). Furthermore, the mechanism of the catalytic reaction has been elucidated through density functional theory (DFT) calculations. The catalytic cycle has been shown to proceed through an outer-sphere mechanism comprising four key transformations, which involve Ru-(II) intermediates based on the deprotonated CNC* ligand: (i) alkoxide dehydrogenation to yield a Ru-(II) hydride complex and an aldehyde molecule, (ii) NO insertion into the ruthenium-hydride bond to yield a hydroxy ruthenium species and N, (iii) nucleophilic attack of the hydroxo ligand in the Ru-OH complex to the intermediate aldehyde, and (iv) dehydrogenation of the formed alcoholate to regenerate the catalytically active Ru-(II) hydride and produce the carboxylate product.
基于甲基吡啶衍生的CNC钳形配体的空气稳定型钌（II）配合物[RuH-(CNC)-(CO)]（=PPh，=Br；=CO，=BF），被发现在碱性条件下能催化一系列醇与NO氧化生成羧酸盐。两种[RuH-(CNC)-(CO)]配合物都能与强碱（叔丁醇钾或KHMDS）迅速反应，生成含有去质子化CNC配体的Ru-(II)配合物（当=PPh时）或Ru(0)-CNC衍生物（当=CO时）。此外，通过密度泛函理论（DFT）计算阐明了催化反应的机理。催化循环已被证明通过一个外层球机制进行，该机制包括四个关键转化，涉及基于去质子化CNC配体的Ru-(II)中间体：（i）醇盐脱氢生成Ru-(II)氢化物配合物和醛分子，（ii）NO插入钌-氢键生成羟基钌物种和N，（iii）Ru-OH配合物中的羟基配体对中间醛的亲核攻击，以及（iv）形成的醇盐脱氢以再生催化活性的Ru-(II)氢化物并生成羧酸盐产物。
