Novel Ag(I), Pd(II), Ni(II) complexes of N,N′-bis-(2,2-diethoxyethyl)imidazole-2-ylidene: Synthesis, structures, and their catalytic activity towards Heck reaction |
| |
| Authors: | Wei-Hsuan Yang Sachindranath Pal Wen-Shu Hwang Ivan JB Lin |
| |
| Institution: | a Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan, ROC
b Department of Chemistry, Soochow University, Shih Lin, Taipei, Taiwan, ROC |
| |
| Abstract: | Tetra-ether substituted imidazolium salts, LHX (where LH = N,N′-bis(2,2-diethoxyethyl)imidazolium cation and X = Br, BF4, PF6, BPh4, NO3 and NTf2 anions) were derived from imidazole. Attempts to produce aldehyde functionalized imidazolium salt through acid hydrolysis of LHBr resulted an unexpected tetra-hydroxy compound LAHBr and the dialdehyde compound LBHBr. Reaction of LHBr with Ag2O afforded L2Ag]AgBr2] (1). Mononuclear Pd-complex trans-L2PdCl2] (2) and dinuclear Pd-complex (LPdCl2)2] (3) were obtained by 1:1 and 1:2 reaction of in situ generated Ag-carbene with Pd(CH3CN)2Cl2. cis-LPdPPh3Cl2] (4) was synthesized from reaction of PPh3 with dinuclear complex 3. Hydrolysis of 3 under acidic conditions also generates a hydroxy derivative 3A and the aldehyde derivative 3B. Direct heating of LHBr with Ni(OAc)2 · 4H2O at 120 °C under vacuum generated trans-L2NiBr2] (5). These complexes were characterized by NMR, mass, elemental analysis, and X-ray single crystal diffraction analysis. Pd--Pd interaction was observed in 3. All the Pd complexes exhibited excellent catalytic activity in Heck reaction. |
| |
| Keywords: | Ether substituted N-heterocyclic carbene Silver Palladium Nickel Heck reaction |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
