我们提出含有C ^ C *环金属新颖钌络合物的合成和结构表征ñ -杂环碳烯配体,η 6 -arene(p -cymene)配体和一个桥连氯离子。通式[Ru(对-cymene)(C ^ C *)Cl]的配合物是通过一锅合成法从相应的银NHC配合物原位进行重金属化制备的。这些配合物与四[3,5-双(三氟甲基)苯基]硼酸钠(NaBAr F 4)反应,形成具有一般结构[Ru(p- Cymene)(C ^ C *)-μ-Cl-(p -cymene)(C ^ C *)Ru] + [BArF 4 ] -。固态结构确认金属中心周围的伪四面体配位与η 6垂直地取向于C ^ C *配位体和σ-配体我-Pr基“顶上”被保持在双金属络合物。
Eight bidentate NHC/Ru complexes, namely [Ru]-1–[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
Cyclometalated complexes are an important class of (pre)catalysts in many reactions including hydride transfer. The ring size of such complexes could therefore be a relevant aspect to consider while modulating their catalyticactivity. However, any correlation between the cyclometalating ring size and the catalyticactivity should be drawn by careful assessment of the pertinent geometrical parameters, and overall
White on target: Platinum(II) complexes with cyclometalated 1‐phenylimidazole ligands (see picture: R=2,3‐OC6H4) show photophysical properties in the blue region of the visible spectrum, thus giving them the potential to be used as the blue component of white‐light‐emitting diodes.
达到目标的白色:具有环金属化的1-苯基咪唑配体的铂(II)配合物(见图:R = 2,3-OC 6 H 4)在可见光谱的蓝色区域显示光物理性质,因此具有潜在的应用前景作为发白光二极管的蓝色成分。
Exploring a unique reactivity of N-heterocyclic carbenes (NHC) in rhodium(<scp>iii</scp>)-catalyzed intermolecular C–H activation/annulation
作者:Debasish Ghorai、Joyanta Choudhury
DOI:10.1039/c4cc07170k
日期:——
Disclosed herein is the unique conjugative role of N-heterocyclic carbene (NHC) ligands as a directing group in aromatic C-H activation, coupled with a facile NHC-alkenyl annulative reductive elimination which guided the Rh(III)-catalyzedintermolecularannulations of imidazolium salts and alkynes under ambient conditions leading to structurally important imidazo[1,2-a]quinolinium motifs.
Unraveling the Competition of Two C–H and Two M–C Bonds in Guiding the Mechanism of Rhodium(III)-Catalyzed C–H Activation–Annulation
作者:Ranjeesh Thenarukandiyil、Suraj K. Gupta、Joyanta Choudhury
DOI:10.1021/acscatal.6b01486
日期:2016.8.5
functionalization protocols of these molecules. In a program to overcome this challenge, recently we developed a unique dual role of a latent imidazolium C–Hbond which not only generated a metal–CNHC bond upon activation but also directed further aryl/heteroaryl C–Hactivation to furnish a library of potentially valuable products. Mechanistic investigation of any newly discovered catalytic reaction is at the heart
已知含咪唑基序的分子在各个研究领域中都引起了极大的兴趣,但是缺少这些分子的功能化方案。在克服这一挑战的计划中,最近我们开发了咪唑鎓潜在的C–H键的独特双重作用,它不仅产生了金属– C NHC活化后结合,也可以进一步指导芳基/杂芳基C–H的活化,以提供潜在有价值的产品库。对任何新发现的催化反应进行机械研究是其未来发展的核心,以潜在地应用于各种领域。受这一理念的激励,我们在本工作中描述了这种环化反应的关键机理,从而揭示了两个C–H键(咪唑鎓和芳基C–H)和两个M–C键(MC– NHC和M–C芳基)建立反应中的限速步骤和插入炔烃的区域选择性。通过对关键的七元插入中间体进行仔细的分离和X射线结构表征以及DFT原理,确定了炔烃插入分子对MHC NHC的排他选择性。动力学研究被用来评估反应的速率确定步骤,这是最初的非定向咪唑CH–H活化步骤。这些机理上的见解应有助于理解通常在催化领域中类似的类似的C–H活化过程。