Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, D-72076 Tübingen, Germany.
Molecules. 2021 Mar 17;26(6):1669. doi: 10.3390/molecules26061669.
The coordination chemistry of an electron-rich macrocyclic CNC pincer-ligand consisting of two pentamethylene tethered N-heterocyclic carbene moieties on a carbazole backbone (bimca) is investigated by mainly NMR spectroscopy and X-ray crystal structure analysis. A bridging coordination mode is found for the lithium complex. With the larger and softer potassium ion, the ligand adopts a facial coordination mode and a polymeric structure by intermolecular potassium nitrogen interactions. The facial coordination is also confirmed at a Cp*Ru fragment, while C-H activation under dehydrogenation at the alkyl chain is observed upon reaction with [Ru(PPh)Cl]. In contrast, Pd(OAc) reacts under C-H activation at the central carbon atom of the pentamethylene tether to an alkyl-pincer macrocycle.
通过主要的 NMR 光谱和 X 射线晶体结构分析研究了由咔唑骨架上的两个五亚甲基桥连的 N-杂环卡宾部分组成的富电子大环 CNC 钳式配体（bimca）的配位化学。发现锂配合物采用桥接配位模式。对于较大和较软的钾离子，配体通过分子间钾氮相互作用采用面式配位模式和聚合结构。在 Cp*Ru 片段中也证实了面式配位，而在与[Ru(PPh)Cl]反应时，在烷基链脱氢时观察到 C-H 活化。相比之下，Pd(OAc)在五亚甲基桥接的中心碳原子上发生 C-H 活化反应，生成烷基-钳式大环。
