| Research Abstract |
Importance of molecular catalysis is widely recognized in efficient production of chemicals and materials in next generation. Organometallic clusters which include dual metallic species in a molecule are one of the promising candidates for new molecular catalysis, arid their synthesis, reactions, and catalysis have received much attention of chemists. We have a concept for the molecular catalyst design, which can be applicable to both mono and multinuclear organometallic catalysts : highly reactive metallic species is generated by appropriate design of auxiliary ligands of metallic species, which stabilize the metallic species in the absence of reactants, but reversibly form reactive species in reaction with substrates. As such "flexible" ligands, we have investigated heteroconjugate ligands such as amidinates and sulfonamides and polyaromatic hydrocarbon ligands such as azulenes and acenaphthylenes. The research has successfully produced new organometallic complexes, which can reversi
… More
bly generate highly reactive species by dynamic behavior of the ligand. Furthermore, these new complexes were proved to be active towards several organic reactions and polymerizations. The results are summarized as follows : (1)Mono and dinuclear ruthenium amidinates were synthesized, several of which were coordinatively unsaturated and highly reactive. Fundamental chemistry including structural analysis, dynamic behavior, and reactions made possible discovery of their catalysis towards chemical transformation of allylic substrates and radical-type reactions. (2)Titanium sulfonamides were newly synthesized and subjected to studies of their structure and solution dynamics. They were proved to be active towards olefin polymerization. (3)Reaction of triruthenium carbonyl clusters bound to acenaphthylenes and azulenes with orgnosilanes were investigated, and the results, i.e.coordinative flexibility of these π-ligands, were applied to highly efficient catalytic reduction of carboxylic derivatives, and silane-induced polymerization of cyclic ethers and siloxanes. (4)Fundamental chemistry on the coordinative flexibility of conjugated π-ligands and new aspects in heterobimetallic chemistry were studied on diiron compounds and Ti-M dinulcear complexes, respectively. Thus, discovery of highly reactive complexes by the ligandl design actually provides fruitful reaction chemistry of these flexible ligands and actual application to molecular catalysis. These contribute to progress of chemistry of molecular catalysis. Less
|
