Synthesis Of Pincer-Nickel Complexes And Their Catalytic Applications In The Activation Of C-Cl And C-O Bonds

This thesis presents (1) synthesis and characterization of a series of N,N,N-pincer ligands and their nickel complexes, and (2) the catalysis of these complexes and N,N,P-pincer nickel complexes [Ni(Cl){N(2-R2PC6H4)(2’-Me2NC6H4)}] (R= Ph, iPr, Cy) in the activation and transformation of C-Cl and C-O bonds.Chapter 1 describes synthesis and characterization of N,N,N-pincer nickel complexes 1.1-1.4. These complexes were characterized by 1H and 13C NMR spectroscopy and elemental analyses. The structure of complex 1.2 was further confirmed by single crystal X-ray diffraction techniques.Chapter 2 is about the cross-coupling of aryl sulfamates with arylzinc chlorides catalyzed by complexes 1.1-1.4. Complex 1.2, as a phosphorus free and air stable catalyst, can effectively catalyze cross-coupling of activated, unactivated and deactivated aryl sulfamates and heteroaryl sulfamates with arylzinc chlorides, forming biaryls in high yields. The reactions required low catalyst loadings and mild reaction conditions in most cases. A range of functional groups including MeO, Me2N, PhC(O), COOMe, CN, CF3, and F as well as nitrogen-containing heterocycles can be tolerated.Chapter 3 presents catalysis of pincer nickel complexes in the activation and transformation of C-Cl bonds of aryl and allyl chlorides. Complex [Ni(Cl){N(2-Ph2P-C6H4)(2’-Me2NC6H4)}] (39a) can catalyze the direct cross-coupling of aryl lithium reagents with aryl chlorides under mild conditions. The method is suitable for electron-rich and-poor aryl chlorides and heteroaryl chlorides. Complex 1.2 shows good catalytic activity in the cross-coupling of aryl zinc reagents with allyl chlorides. The reaction requires relatively low catalyst loadings and mild reaction conditions.Chapter 4 deals with cross-coupling of allyl methyl ethers with arylzinc reagents catalyzed by complex 39a. The reaction showed high regioselectivity when (l-methoxyallyl)arenes or (3-methoxyprop-1-en-1-yl)arenes were employed as the electrophilic substrates, giving linear (E)-alkenes in high yields. Aliphatic group substituted allyl methyl ether (E)-1-methoxytridec-2-ene also exhibited good reactivity with p-Me2NC6H4ZnCl under the same conditions, but formed a mixture of linear and branched regioisomers.