1,3-Diarylimidazolidin-2-ylidene (NHC) complexes of Pd(II): Electronic effects on cross-coupling reactions and thermal decompositions
作者:Hayati Türkmen、Bekir Çetinkaya
DOI:10.1016/j.jorganchem.2006.05.020
日期:2006.9
1,3-diarylimidazolidin-2-ylidene (NHC) precursor, 1,3-bis(2,4,6-trimethylphenyl)imidazolinium chloride, (3b) has been extended to the electronically and sterically modified NHC precursors 3a (X = H), 3c (X = Br) and 3e (X = Cl) in order to investigate the electronic effect of a p-substituent (X) on cross-coupling catalysts. Complexes of the type PdCl2(NHC)2 (5), PdCl2(NHC)(PPh3) (6) and [RhCl(NHC)(cod)]
1,3-二芳基咪唑啉-2-亚甲基(NHC)前体1,3-双(2,4,6-三甲基苯基)咪唑啉鎓氯化物(3b)的合成已扩展到电子和空间修饰的NHC前体3a( X = H),3c(X = Br)和3e(X = Cl)是为了研究对位取代基(X)对交叉偶联催化剂的电子作用。从3或4d制备PdCl 2(NHC)2(5),PdCl 2(NHC)(PPh 3)(6)和[RhCl(NHC)(cod)](7)类型的配合物。(1,3-双(2,4-二甲基苯基)-2-三氯甲基咪唑烷)。配合物5和6的初始分解温度通过TGA确定。已经测试了Pd(OAc)2和3以及预形成的配合物5和6的原位形成的配合物作为苯基硼酸与4-卤代苯乙酮偶联的催化剂。通过测量相应的[RhCl(NHC)(CO)2 ]配合物8中的C–O频率来评估3衍生的NHC的电子给体能力,该配合物是通过替换7的鳕鱼配体制备的观察到芳基取代基的供电子性质与催化活性以