The Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China.
Dalton Trans. 2013 Jun 21;42(23):8437-45. doi: 10.1039/c3dt00086a. Epub 2013 Apr 26.
Novel ionic Ni(II) complexes of general formula [R2im][Ni(PPh3)Cl3] (R2im = 1,3-bis(2,6-diisopropylphenyl)imidazolium cation, IPrim, 1a; R2im = 1,3-diisopropylimidazolium cation, (i)Prim, 2a) were easily prepared in high yields by the direct reaction of Ni(PPh3)2Cl2 with 1 equiv. of N,N'-dihydrocarbylimidazolium salt, [R2im]Cl. Their bromide analogs [R2im][Ni(PPh3)Br3] (R2im = IPrim, 1b; R2im = (i)Prim, 2b) were synthesized by the same reaction in the presence of excess NaBr. The reaction of Ni(DME)Cl2 (DME = 1,2-dimethoxyethane) with 2 equiv. of [IPrim]Cl led to the formation of the complex [IPrim]2[NiCl4] (3) in an almost quantitative yield. All these complexes were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), and (1)H NMR spectroscopy; X-ray crystallography was performed for 1a, 1b, 2a, and 2b. A catalytic study of the cross-coupling reactions of aryl Grignard reagents with aryl halides revealed that complexes 1a and 1b possessed the highest activities. In comparison, complexes 2a, 2b, 3, and the related biscarbene Ni(II) complex Ni(IPr)2Cl2 [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] exhibited moderate activities; the least active complexes were Ni(PPh3)2Cl2 and [NEt4][Ni(PPh3)Cl3].
新型离子镍（II）配合物的通式为[R2im][Ni（PPh3）Cl3]（R2im = 1,3-双（2,6-二异丙基苯基）咪唑鎓阳离子，IPrim，1a; R2im = 1,3-二异丙基咪唑鎓阳离子，（i）Prim，2a）可通过 Ni（PPh3）2Cl2 与 1 当量的 N，N'-二氢碳酰基咪唑鎓盐[R2im]Cl 的直接反应以高产率轻易制备。它们的溴化物类似物[R2im][Ni（PPh3）Br3]（R2im = IPrim，1b; R2im = （i）Prim，2b）通过相同的反应在过量的 NaBr 存在下合成。Ni（DME）Cl2（DME = 1,2-二甲氧基乙烷）与 2 当量的[IPrim]Cl 的反应几乎定量地生成配合物[IPrim]2[NiCl4]（3）。所有这些配合物均通过元素分析、电喷雾电离质谱（ESI-MS）和（1）H NMR 光谱进行了表征；X 射线晶体学用于 1a、1b、2a 和 2b。芳基格氏试剂与芳基卤化物的交叉偶联反应的催化研究表明，配合物 1a 和 1b 具有最高的活性。相比之下，配合物 2a、2b、3 和相关的双碳烯 Ni（II）配合物 Ni（IPr）2Cl2[IPr = 1,3-双（2,6-二异丙基苯基）咪唑-2-亚基]表现出中等活性；最不活跃的配合物是 Ni（PPh3）2Cl2 和[NEt4][Ni（PPh3）Cl3]。
