| Research Abstract |
Preparation of new organometallic complexes bearing conjugate π-ligands was achieved, which showed unique catalytic reactivity in homogeneous carbon-carbon bond forming reactions and related reactions. First, multinuclear ruthenium clusters bearing azulenes or acenapthylenes were synthesized, some of which were proved to achieve facile activation molecular hydrogen or hydrosilanes. Hapticity change of the brigding conjugate π-systems was evidenced in either the haptotropic rearrangements of diiron or diruthenium compounds or in the product analysis of hydrogenation of di-, tri-, or tetraruthenium clusters. Facile activation of the H-Si bond of organosilanes led to catalytic hydrosilylation of carbonyl compounds, reductive silylation of acetals and cyclic ethers, ring-opening polymerization of cyclic ethers and siloxanes. Second, highly reactive organoruthenium amidinates were newly synthesized, and coordinative flexibility of the amidinate ligands were proved experimentally. High react
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ivity of these new compounds were useful for facile activation of several organic substrates including catalytic allylation of nucleophiles. The reaction with an organoruthenium species led to novel type of diruthenium complexes bearing bridging amidinate ligands. Third, coordination behavior of sulfoamide ligands was examined in titanium compounds, which provided important aspects in coordinative flexibility of the sulfoamide ligands. Polymerization of ethylene was accomplished. Forth, polyhalogenated γ-lactams were catalytically synthesized by copper-bipyridine complexes. Systematic investigation on electronic and steric properties of either the bipyridine ligands or the substrates contributes to better understanding of the catalysis. These results provided new concepts for the development of homogeneous catalytic carbon-carbon bond forming reactions and related reactions, in which coordinative flexibility inducing facile hapticity change of the π-ligands is an essential clue to discover new catalysts and new catalytic reactions. Less
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