Tetranuclear Palladium Complexes of Abnormal N-heterocyclic Carbene Ligands and their Catalytic Activities in Mizoroki-Heck Coupling Reaction of Electron-Rich Aryl Chlorides

• Main Authors: Su,Yong-Siang, 蘇永祥
• Other Authors: Lee,Hon-Man
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/j6h2kp

碩士 === 國立彰化師範大學 === 化學系 === 107 === Based on the ligand scaffold of an imidazolyl/benziimidazolyl moiety and a N-CH2C(=O)NHPh substituent, two novel series of ligand precursors with an ortho hydroxy group incorporated on the N-phenyl ring were prepared. The structural fine tuning of the ligand scaffold allowed the facile synthesis of the first example of tetranuclear palladium complexes with abnormal NHC (aNHC) ligands. For those precursors with C2-methyl blocking group, pyridine-assisted C—H bond activation led to the formation of mononuclear tridentate palladium aNHC complexes or tetranuclear complexes with tridentate CNO donors. Representative mononuclear and tetranuclear palladium aNHC complexes were structurally characterized by X-ray diffraction studies, revealing extremely short Pd─C bond distances. The tetranuclear palladium aNHC complexes were extremely effective in catalyzing Mizoroki-Heck coupling reaction, capable of the use of a range of aryl chlorides including deactivated substrates with a low Pd loading of 0.2 mol%.