Reactive Organometallics of Transition Metals

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Aiming to acquire innovative method of chemical transformation for the future, the research group designed and prepared reactive organometallics of transition metals, and their functions as reagents and catalysts have been investigated. The representative results are as follows. Low valent transition metal polyhydrides have proven to act as either redox Lewis acid or base catalysts by their specific ability to activate of alpha-C-H and CN bonds of nitriles. The principle has led to development of a variety of novel catalytic reactions such as aldol condensation, Michael addition, and transformations of CN functionalities with nucleophiles which proceed under neutral conditions (Murahashi). Lanthanide organometallics bearing bulky metallocenes were found to show high activity for polymerization of ethylene and methacrylates. The corresponding polymers have been obtained with high molecular weight, high syndiotacticity, and narrow polydispencity (Yasuda). A series of polyhydrido organome … More tallics of group 6 transition metals have been prepared. The coordinatively unsaturated active species have been created by light irradiation, and their reactivities towards oxidative addition to organic substrates such as alcohols and amides have been investigated (Ito). The active catalytic species derived from the reaction of vinyl sulfides with Lewis acids have proven to be versatile synthetic intermediates for construction of carbon skeletons using ene reactions, [3+2] cycloaddition and ring closing coupling reactions (Kuwajima). Novel trinuclear ruthenium complexes bearing bridging polyhydrido ligands have been created, and these complexes show specific reactivity towards carbon-carbon bond cleavage and C-H activation of cyclopentadiene via multimetallic cooperation (Suzuki). Bimetallic platinum-palladium organometallics bearing mu-ethynediyl ligands have been prepared. High catalytic activity towards living polymerization of aryl isocyanides was observed with these unique complexes (Takahashi). Less