New Materials Starting from Organometallic Complexes

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This project has been done with the object of synthesizing new functional materials starting from organometallic compounds.1) Organolanthanide complexes of type (C_5R_5) _2LnR has first been found to catalyze the polymerization of Methyl Methacrylate (MMA) leading to high molecular weight polymers with extremely narrow polydispersity in excellent yield. Further more, preparation of highly stereoregular polymers (syndiotacticity, >95%) was also succesful by conducting the polymerization at low temperature. Block copolymerization of ethylene with MMA was also realized by introducing MMA into the samarium initiated polyethylene living end. This is the first example of copolymerization between non-polar and polar monomers. 2) Pyrolysis of organometallic polymers or polymeric metal complexes provides new carbon composites containing ultra-fine metal particles, which are dispersed homogeneously in the carbon matrices. Characteristics of these materials lie in their high stability in aerobic conditions. Carbon composites containing Pt, Pd, Rh, Ru or Fe particles serve as good catalysts for hydrogenation of olefins and decomposition of H_2O_2. Ag contained materials show good bacteriostatic activity for various bacteria.3) In order to evaluate the unique behavior of group 5 early transition metal complexes, a series of Nb-alkyne complexes was synthesized starting from a Nb-ethylene complex. As a result, the mode of reactions could be classified into 3 groups. Ethylniobiumalkyne complexes exhibits an unusual alpha-agonstic interaction between ethyl group and metal. This result indicates that formation of new Nb-carbene complexes is possible through this type of bonding.