Nickel(II) Benzimidazolin-2-ylidene Complexes with Thioether-Functionalized Side Chains as Catalysts for Suzuki-Miyaura Cross-Coupling
Nickel(II) Benzimidazolin-2-ylidene Complexes with Thioether-Functionalized Side Chains as Catalysts for Suzuki-Miyaura Cross-Coupling
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DOI：
10.1021/om500484q
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发表时间：
2014-10-27
期刊：
影响因子：
2.8
通讯作者：
Huynh, Han Vinh
中科院分区：
文献类型：
--
作者：
Bernhammer, Jan C.;Huynh, Han Vinh
以四丁基溴化铵为离子液体，通过苯并咪唑鎓盐与乙酸镍反应，合成了四种侧链含硫醚的双（苯并咪唑啉-2-亚基）镍配合物。所有的配合物作为反式-顺式和反式-反式旋转异构体的不可分离的混合物获得，如通过NMR光谱所证明的。对于其中一个配合物，X射线衍射证实了正方形平面配位几何结构。研究了所有配合物对SuzukiMiyaura交叉偶联的催化活性。在优化的反应条件下，以三苯基膦为添加剂，成功地实现了溴代芳醚和氯代芳醚的偶联。产率范围从良好到中等的缺电子的芳基卤化物，而富电子的芳基卤化物被发现是不活泼的。
Four bis(benzimidazolin-2-ylidene) nickel(II) complexes featuring thioether moieties in the side chain have been synthesized by reactions of the respective benzimidazolium salts with nickel(II) acetate in molten tetrabutylammonium bromide as an ionic liquid. All complexes were obtained as inseparable mixtures of trans-syn and trans-anti rotamers, as evidenced by NMR spectroscopy. For one of the complexes, X-ray diffraction confirmed the square-planar coordination geometry. The catalytic activity of all complexes for SuzukiMiyaura cross-coupling was examined. Under the optimized conditions, both aryl bromides and aryl chlorides were successfully coupled in the presence of triphenylphosphine as additive. Yields ranged from good to moderate for electron-deficient aryl halides, while electron-rich aryl halides were found to be unreactive.