| Research Abstract |
Molecular catalysts using organometallic precursors are one of the most important tools for modern organic and polymer synthesis. Recent requirement for protection of global environment urges to develop reusable molecular catalysts, which do not leach the metallic residues to the product. The present research deals with the catalytic reactions using the polymeric organometallic reagents, which are useful for fixing the organometallic species in the polymer matrix for facile removal from the product after the reaction. We are interested in di- and polynuclear organometallic clusters as a potential precatalyst, whereas organosiloxanes and aluminoxanes as a suitable organometallic polymers. The research consists of four steps, (a) catalyst design and synthesis, (b) analysis of molecular structures and electronic structures, (c)catalytic reactions with non-polymeric reagents, (d) catalytic reactions with polymeric reagents. The project was first focused on the catalytic reduction of carbox
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amides with a triruthenium carbonyl cluster, (μ_3, η_2, η_3, η_5-acenaphthylene)Ru_3(CO)7, which is proved to be the one of the most active and versatile catalysts for this purpose. Secondary and tertiary amides are smoothly converted to the corresponding amines in high yields. Under certain conditions, the reduction of carboxamides proceeds with the other functional groups remaining intact. Application of polymethylhydrosiloxane (PMHS) as the reducing reagent results in formation of siloxane gel, to which all of the catalytic species are soaked up. The gel containing metallic species is facilely removable from the product, and reusable as the catalyst. The results were expanded in catalytic reduction of amides with PMHS using other molecular catalysts, providing platinum-catalyzed formation of amines and iridium-catalyzed production of enemies. Organoaluminium polymer, methylaluminoxane(MAO), is a famous cocatalyst for catalytic olefin polymerization. Catalyst design of two types of organometallic compounds, organonickel complexes derived from isocyanides and early-late heterobimetallic complexes, was achieved and subjected to studies on the ethylene polymerization in the presence of MAO. The metallic species in the siloxane or aluminoxane matrix was investigated. Less
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