Part one. Catalytic activation of organosilicon and organohalide compounds with dinuclear nickel hydride Part two. Mechanistic study and kinetic modeling of single-site catalytic olefin polymerization with zirconium salan.

摘要

We have shown the dinuclear nickel catalyst, [(dippe)NiH]2, to be effective in both hydrosilylation and dehydrocoupling reaction with organosilanes. The mechanism for nickel-catalyzed hydrosilylation of benzaldehyde has been studied by chemical kinetics, identification of reaction intermediates, and isotope-labeling studies. The mechanism for nickel-catalyzed dehydrocoupling of organosilanes was studied by consumption and dihydrogen evolution kinetics and intermediate identification. The dehydrocoupling reaction can proceed by either sigma-bond metathesis or an oxidative-addition mechanism with a nickel silyl hydride intermediate.;Organometallic zirconium-salan complexes catalyze 1-hexene polymerization under batch conditions. A major roadblock in the field of rational olefin polymerization catalyst design is the lack of reliable kinetic constants that adequately describe experimental observations under catalytic conditions. We have studied the kinetics of 1-hexene polymerization with the Cl 4[ONNMeO]ZrBn2/B(C6F5) 3 catalyst system by following monomer consumption, determining active-site counts, and molecular weight distributions (MWD) as a function of time. A kinetic model is employed to fit all of the data simultaneously providing robust kinetic constants and determining the important mechanistic steps in the catalytic cycle.