Chen Zhe, Ouyang Laofeng, Wang Ning, Li Weikang, Ke Zhuofeng
School of Materials Science and Engineering, PCFM Lab, the Key Laboratory of Low-carbon Chemistry & Energy Conservation of Guangdong Province, Sun Yat-sen University Guangzhou 510006 P. R. China
School of Chemistry, Sun Yat-sen University Guangzhou 510275 P. R. China.
Chem Sci. 2024 Nov 22;16(1):163-170. doi: 10.1039/d4sc05486e. eCollection 2024 Dec 18.
Metal-ligand cooperation (MLC) is an essential strategy in transition metal catalysis. Traditional NH-based and OH-based MLC catalysts, as well as the later developed (de)aromatization strategy, have been widely applied in atom-economic borrowing hydrogen/hydrogen auto-transfer (BH/HA) reactions. However, these conventional MLC approaches are challenging for low-coordination and low-activity coinage metal complexes, arising from the instability during (de)protonation on the coordination atom, the constraint in linear coordination, and possible poisoning due to extra functional sites. Herein, we demonstrate a remote C-H bond cooperation strategy that enables the unprecedented homogeneous Ag(i)-catalyzed BH/HA reaction. The covalent C-H bifunctional site well facilitates (de)hydrogenation, especially under the low coordination circumstances of d Ag(i). The strong electron-donating bis--heterocyclic carbene (NHC) ligand stabilizes the silver-hydride and stimulates the hydride activity on the -position of ligands. Mechanistic studies implicate the plausible remote assistance of the dissociative NHC arm in facilitating BH/HA reactions. Our findings emphasize the potential of the remote C-H bond cooperation strategy for low coordination metals in catalyzing BH/HA reactions and broadening MLC catalysts to d coinage metals.
金属-配体协同作用(MLC)是过渡金属催化中的一项重要策略。传统的基于NH和OH的MLC催化剂,以及后来发展的(去)芳构化策略,已广泛应用于原子经济性的借氢/氢自动转移(BH/HA)反应。然而,这些传统的MLC方法对于低配位和低活性的贵金属配合物具有挑战性,这是由于配位原子上(去)质子化过程中的不稳定性、线性配位的限制以及额外功能位点可能导致的中毒。在此,我们展示了一种远程C-H键协同策略,该策略实现了前所未有的均相Ag(i)催化的BH/HA反应。共价C-H双功能位点极大地促进了(去)氢化反应,特别是在d Ag(i)低配位的情况下。强供电子的双-杂环卡宾(NHC)配体稳定了氢化银,并激发了配体α位上的氢化物活性。机理研究表明,解离的NHC臂可能在促进BH/HA反应中起到远程辅助作用。我们的研究结果强调了远程C-H键协同策略在催化BH/HA反应以及将MLC催化剂扩展到d区贵金属方面对于低配位金属的潜力。