Three thioether bridged diimidazolium dibromides with different steric and electronic properties have been synthesized as precursors to carbene-based CSC pincer ligands. Palladation afforded CSC Pd(II) pincer complexes for bulky and electron rich ligand systems, whereas the least donating ligand led to the formation of a pseudo-pincer complex. All complexes have been fully characterized by multinuclei NMR spectroscopies, ESI mass spectrometry and X-ray diffraction analysis. The catalytic activities of pincer versus pseudo-pincer complexes have been compared in the intermolecular hydroamination of alkynes with anilines as well.
三种具有不同立体和电子性质的三
硫醚桥连二
咪唑鎓二
溴化物已被合成作为基于卡宾的CSC钳形
配体的前体。对这些
配体进行
钯化得到CSC Pd(II)钳形配合物,适用于空间位阻大且电子富集的
配体系统,而电子捐赠能力最弱的
配体则导致了伪钳形配合物的形成。所有配合物都通过多核NMR光谱、ESI质谱和X射线衍射分析得到了充分表征。此外,钳形配合物与伪钳形配合物的催化活性也在
炔烃与
苯胺的分子间
氢胺化反应中进行了比较。