Synthesis Of Nickel Complexes And Activation And Transformation Of C-Cl And C-N Bond

This thesis describes synthesis and characterization of new nickel complexes bearing P,N,N-and N,N,N-pincer ligands and catalysis of the complexes towards Kumada reaction and Negishi reaction. Nickel-catalyzed amination reaction of aryltrimethylammonium salts is also presented.Chapter1describes synthesis and characterization of anionic P,N,N-and N,N,N-ligands and their nickel complexes. The nickel complexes were synthesized through reaction of the anionic P,N,N-and N,N,N-ligands with NiCl2(DME), including:[Ni(Cl){2-(PPh2)C6H4NC(Ph)=NAr](1.1a, Ar=p-MeC6H4;1.1b, Ar=p-ClC6H4;1.1c, Ar=p-MeOC6H4),[Ni(Cl){2-(PPh2)C6H4NC(Ph)CN(CH)2NMe}](1.2),[Ni(Cl){2-(p-MeC6H4N=PPh2)C6H4NC(Ph)CN(CH)2NMe}](1.3). Complexes1.1a-1.3were characterized by NMR spectroscopy and elemental analyses. The structures of complexes1.1a and1.3were further characterized by single-crystal X-ray diffraction techniques.Chapter2is about catalysis of nickel complexes1.1a-1.3towards the Kumada cross-coupling reaction and nickel complexes2.1-2.5towards the Negishi cross-coupling reaction. Among the complexes tested, the P,N,N-pincer nickel complexes1.2and N,N,N-pincer nickel complexes1.3exhibited relatively low catalytic activity. By contrast, the P,N,N-pincer nickel complexes1.1a-1.1c showed excellent catalytic activity for the coupling reactions of activated and deactivated aryl, vinyl, and heteroary chlorides with aryl Grignard reagents. The nickel complexes2.5is able to efficiently catalyze Negishi cross-coupling.Chapter3deals with catalysis of nickel complexes1.1a-1.3towards the cross-coupling reaction of aryltrimethylammonium salts with aryl zinc reagents. Nickel complexe1.1a leads to cross-coupling of aryltrimethylammonium iodides as well as2-pyridyltrimethylammonium iodide with aryl-or heteroarylzinc reagents in moderate to excellent yields. The reactions require low catalyst loadings in most cases and tolerate functional groups such as ester, keto, and CF3groups.Chapter4presents amination reaction of aryltrimethylammonium triflates catalyzed by Ni(COD)2/IPr·HCl in the presence of sodium tert-butoxide. This catalyst system suits for a broad scope of substrates. The ammonium salts used in this transformation include activated, unactivated, and deactivated aryltrimethyl- ammonium triflates as well as2-pyridyltrimethylammonium triflate. The aminated reagents include primary and secondary amines, aliphatic and aromatic amines, and cyclic and acyclic amines. The reaction can also be carried out by a one-pot procedure starting from an aryldimethylamine.