1,8-Bis(imidazolin-2-yliden-1-yl)carbazolide (bimca): A New CNC Pincer-Type Ligand with Strong Electron-Donating Properties. Facile Oxidative Addition of Methyl Iodide to Rh(bimca)(CO)†
1,8-Bis(imidazolin-2-yliden-1-yl)carbazolide (bimca): A New CNC Pincer-Type Ligand with Strong Electron-Donating Properties. Facile Oxidative Addition of Methyl Iodide to Rh(bimca)(CO)†
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DOI：
10.1021/om060952z
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发表时间：
2007-01
期刊：
影响因子：
2.8
通讯作者：
M. Moser;Barbara Wucher;Doris Kunz;F. Rominger
中科院分区：
文献类型：
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作者：
M. Moser;Barbara Wucher;Doris Kunz;F. Rominger
提出了一种基于N-杂环卡宾取代咔唑的新型CNC钳型配体的合成。所得 3,6-二叔丁基-1,8-双(3-甲基咪唑啉-2-亚基-1-基)咔唑化物 (bimca) 是单阴离子、经向配位三齿配体，通过咪唑鎓盐 (bimca)·2HI (3a) 或 (bimca)·2HBF4 (3b) 去质子化原位生成，其特征为NMR 谱为 Li 配合物 4。与 [Rh(CO)2Cl]2 反应成功金属转移为铑，生成 Rh(bimca)(CO) (5)。该配合物在 ν(CO) 波段的红外光谱中显示出非常小的波数，从而表明 bimca 配体的强 σ 供体和弱 π 受体特性。 Rh(I) 中心的高度亲核特性通过甲基碘与 Rh(bimca)(CO) (5) 的正式氧化加成得到了证明，该反应比迄今为止报道的任何其他 Rh(I) 配合物进行得更快。络合物 Rh(bimca)(CH3)I(CO) (6) 以及 Rh(bimca)(CO) (5) 通过 X-... 进行表征。
The synthesis of a new CNC pincer-type ligand based on an N-heterocyclic carbene substituted carbazole is presented. The resulting 3,6-di-tert-butyl-1,8-bis(3-methylimidazolin-2-yliden-1-yl)carbazolide (bimca) is a monoanionic, meridionally coordinating tridentate ligand that was generated in situ by deprotonation of the imidazolium salt (bimca)·2HI (3a) or (bimca)·2HBF4 (3b) and characterized by NMR spectroscopy as the Li complex 4. The successful transmetalation to rhodium upon reaction with [Rh(CO)2Cl]2 yielded Rh(bimca)(CO) (5). This complex shows a very small wavenumber in the IR spectrum for the ν(CO) band, thus indicating strong σ-donor and weak π-acceptor properties of the bimca ligand. The highly nucleophilic character of the Rh(I) center was proven by the formal oxidative addition of methyl iodide to Rh(bimca)(CO) (5), a reaction that proceeded more quickly than with any other Rh(I) complex reported so far. The complex Rh(bimca)(CH3)I(CO) (6) as well as Rh(bimca)(CO) (5) were characterized by X-...