Benaissa Idir, Taakili Rachid, Lugan Noël, Canac Yves
LCC-CNRS, Université de Toulouse, INPT, UPS, 205 route de Narbonne, 31077 Toulouse Cedex 4, France.
Dalton Trans. 2017 Sep 28;46(36):12293-12305. doi: 10.1039/c7dt02759a. Epub 2017 Sep 8.
A series of NHC pre-ligands featuring a pendant phosphonium moiety attached to N' position through a propyl linker was readily obtained upon quaternization of N-mesityl- and N-methyl-imidazole, or N-mesityl-imidazoline using (3-bromo-propyl)-triphenylphosphonium bromide. Reactions of the resulting dicationic salts with [PdCl(allyl)] in the presence of KCO afforded the anticipated NHC-ligated Pd(ii) metal complexes in high yields. Further treatment of the latter complexes with tBuOK induced a deprotonation of the carbon atom adjacent to the phosphonium moiety and the formation of the corresponding C,C-chelating NHC-phosphonium ylide Pd(ii) complexes. Investigation of an alternative synthetic route involving a silver transmetallation reaction incidentally allowed isolation and full characterization of an unusual dimeric tetranuclear NHC Ag(i) complex of general formula [(NHC∼P)(AgBr)].
通过用（3-溴丙基）三苯基溴化鏻对N-均三甲苯基-和N-甲基-咪唑或N-均三甲苯基-咪唑啉进行季铵化反应，很容易得到一系列在N'位通过丙基连接基连接有一个季鏻部分的NHC前体配体。在碳酸钾存在下，所得的双阳离子盐与[PdCl(烯丙基)]反应，以高产率得到预期的NHC配位的Pd(ii)金属配合物。用叔丁醇钾进一步处理后一种配合物，会使与季鏻部分相邻的碳原子去质子化，并形成相应的C,C-螯合NHC-鏻叶立德Pd(ii)配合物。对涉及银转金属化反应的另一种合成路线的研究偶然地实现了一种通式为[(NHC∼P)(AgBr)]的不寻常的二聚四核NHC Ag(i)配合物的分离和全面表征。
