LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France.
Dalton Trans. 2019 Feb 7;48(5):1709-1721. doi: 10.1039/c8dt04316g. Epub 2019 Jan 11.
A new family of pincer palladium(ii) complexes bearing an electron-rich C,C,C-NHC, diphosphonium bis(ylide) ligand of LX-type was prepared through the dual N-functionalization of 1H-imidazole by (3-bromopropyl)triphenylphosphonium bromide. Selected basic conditions allowed the sequential coordination of the NHC and phosphonium ylide moieties to Pd(ii). This strategy led to an original ortho-metallated complex where the Pd center is bonded to four carbon atoms of three different natures: carbenic (sp), arylic (sp), and chiral ylidic (sp). Protonation of the latter afforded NHC, diphosphonium bis(ylide) pincer Pd(ii) complexes as a mixture of meso- and dl-diastereomers (de = 50%). The selectivity of C-coordination was rationalized on the basis of DFT calculations, evidencing the quasi-degeneracy of the two diastereomeric forms.
一种新型的钳式钯（II）配合物家族，具有富电子的 C，C，C-NHC，二膦双（亚基）配体 LX 型，通过（3-溴丙基）三苯基溴化膦对 1H-咪唑的双重 N-官能化制备。选择基本条件允许 NHC 和膦亚基部分顺序配位到 Pd（ii）上。该策略导致了一个原始的邻位金属化配合物，其中 Pd 中心与三个不同性质的四个碳原子键合：碳（sp），芳基（sp）和手性亚基（sp）。后者的质子化提供了 NHC，二膦双（亚基）钳式 Pd（ii）配合物作为内消旋和 dl-非对映异构体的混合物（de = 50％）。根据 DFT 计算，对 C-配位的选择性进行了合理化，证明了两种非对映异构体形式的准简并性。
