| In Chapter 1, the synthesis and characterization of the bimetallic 2,7-di-[(2,6-diisopropylphenyl)imino]-1,8-naphthalenediolato group 10 metal polymerization catalysts {[Ni(CH3)]2[1,8-(O) 2C10H4-2,7-[CH=N(2,6-iPr2 C6H3)](PMe3)2} and {[Ni(1-naphthyl)] 2[1,8-(O)2C10H4-2,7-[CH=N(2,6- iPr2C6H3)](PPh3) 2} [FI2-Ni2(PR3)2] are presented, along with the synthesis and characterization of the mononuclear analogues {Ni(CH3)[3-tBu-2-(O)C6H 3CH=N(2,6-iPr2C6H3)](PMe) 3} and {Ni(1-naphthyl)[3-tBu-2-(O)C6H 3CH=N(2,6-iPr2C6H3)](PPh) 3} [FI-Ni (PR3)]. Monometallic Ni catalysts were also prepared by functionalizing one ligation center of the bimetallic ligand with a trimethylsilyl group (TMS), yielding {Ni(CH3)[1,8-(O)(TMSO)C 10H4-2,7-[CH=N(2,6-iPr2C6 H3)](PMe3)} [TMS-FI2-Ni(PMe 3)]. The FI2-Ni2 catalysts exhibit significant increases in ethylene homopolymerization activity versus the monometallic analogues, as well as increased branching and methyl branch selectivity, even in the absence of a Ni(cod)2 cocatalyst. Increasing ethylene concentrations significantly suppress branching and branch morphology. FI2-Ni2-mediated copolymerizations with ethylene + polar-functionalized norbornenes exhibit a four-fold increase in comonomer incorporation versus FI-Ni, yielding copolymers with up to 10% norbornene copolymer incorporation. FI2-Ni2-catalyzed copolymerizations with ethylene + methylacrylate or methyl methacrylate incorporate up to 11% acrylate comonomer, while the corresponding mononuclear FI-Ni catalysts incorporate negligible amounts. Furthermore, the FI2-Ni2-mediated polymerizations exhibit appreciable polar solvent tolerance, turning over in the presence of ethyl ether, acetone, and even water. The mechanism by which the present cooperative effects take place is investigated, as is the nature of the copolymer microstructures produced.;In Chapter 2, the second nickel center on the binuclear pheonxyiminato ligand is replaced with a palladium, yielding heterobimetallic 2,7-di-[(2,6-diisopropylphenyl)imino]-1,8-naphthalenediolato group 10 metal polymerization catalysts {[Ni(CH3)][Pd(CH3 )][1,8-(O)2C10H4-2,7-[CH=N(2,6- iPr2C6H3)](PMe3) 2}, FI2-NiPd(PMe3)2. The synthesis and characterization of FI2-NiPd(PMe 3)2 is presented along with that of its corresponding monometallic analogues: FI-Pd (PMe3) and the aforementioned FI-Ni (PMe3). Bimetallic catalyst FI2-NiPd(PMe 3)2 exhibits negligible cooperation during homopolymerizations of ethylene or methacrylate, with activities similar to that of the monometallic systems. However, copolymerizatons show a further increase of acrylate incorporation; up to 14% as compared to 11% in the dinickel systems. Also of interest is the ability to produce acrylate-branched polymer systems due to differences in catalytic activation of each metal center, yielding acrylate-branched polymers of the type (poly-methacrylate)x(polyethylene-co-methacrylate) y. The mechanism by which the co and acrylate-branched polymers are produced is investigated, as is the mechanism for catalyst activation and death. |
