Three new dibenzimidazolium salts bearing thioether (B·2HBr, B·2HNO3) and sulfoxide (C·2HBr) containing bridges have been synthesized as sulfur-functionalized dicarbene precursors. Palladation of B·2HBr and C·2HBr afforded two new pseudo-pincer complexes cis-[PdBr2(B-κ2C)] (1) and cis-[PdBr2(C-κ2C)] (2), in which the sulfur-donor remains pendant. Reaction of precursor B·2HNO3 in the presence of 1 equiv of KBr, on the other hand, yields the first CSC-Pd(II) pincer complex [PdBr(B-κ3CSC)]NO3 (3) bearing two carbene moieties. All three complexes have been fully characterized by multinuclei NMR spectroscopies, ESI mass spectrometry and X-ray diffraction analysis. Their catalytic activities in the Mizoroki–Heck reaction have been evaluated as well.
合成了三种含有
硫醚(B·2HBr,B·2HNO3)和亚砜(C·2HBr)桥联基团的新型二
苯并咪唑盐类含
硫二卡宾前驱体。将B·2HBr和C·2HBr与
钯反应,得到了两种新的伪夹心型配合物顺式-[PdBr2(B-κ2C)](1)和顺式-[PdBr2(C-κ2C)](2),其中
硫供体保持悬挂状态。另一方面,在1当量KBr的存在下,前驱体B·2HNO3反应生成首个含两个卡宾基团的CSC-Pd(II)夹心型配合物[PdBr(B-κ3CSC)]NO3(3)。所有三种配合物均通过多核NMR光谱、ESI质谱和X射线衍射分析进行了全面表征。同时评估了它们在Mizoroki-Heck反应中的催化活性。