| Research Abstract |
1. Synthesis of Tetra-and Pentanuclear Ruthenium Polyhydrido Clusters : The reactivity of cluster complex is most probably affected by the nuclearity because the reactivity strongly depends on the number of transferable electrons between the cluster and substrate. Thus the development of a rational method for the synthesis of clusters with higher nuclearity and a variety of auxiliary ligands seems to be essential for the application of such cluster to organic synthesis. After a four-year term of the research, we developed synthetic methods of a variety of tetra-and pentanuclear ruthenium polyhydrido clusters, such as (CpRu)_4H_6, (CpRu)_3(Cp^*Ru)H_6, (CpRu)_2(Cp^*Ru)_2H_6, (CpRu)(Cp^*Ru)_3H_6, and (CpRu)_5H_7. Electronic properties of these clusters were estimated by means of electrochemical technique.
2. Synthesis of Di-and Trinuclear Heterobimatallic Polyhydrido Clusters Containing Molybdenum, Tungsten, Rhenium, and Ruthenium : Novel heterotrimetallic polyhydrido complexes containing
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ruthenium and group 6 metals,
(Cp^*Ru)_2(Cp^*M)(μ-H)_5 (M = Mo, W) and (Cp^*Ru)(Cp^*W)_2H_7, were synthesize by the reaction of (Cp^*RuOMe)_2 with dinuclear polyhydrido complexes Cp^*Ru(μ-H)_3MH_3Cp^* (M = Mo, W). Polyhydrido complexes containing both ruthenium and rhenium, Cp^*Ru(μ-H)_3ReH_2Cp^* and (Cp^*Ru)_2(Cp^*Re)(μ-H)_7, were also synthesized.
3. Cleavage of the N-N Bond of Hydrazine Induced by Triruthenium Cluster : The reaction of [(Cp^*Ru)_3H_6]+ with hydrazine led to the the formation of (Cp^*Ru)_3(μ-NH)H_3 as a result of cleavage of the N-N bond. This compound further reacted with hydrazine to yield (Cp*Ru)_3(μ-NH)_2H. These μ_3-imido complexes underwent hydrogenation to generate (Cp^*Ru)_3H_5 together with liberation of ammonia.
4. Cleavage of N-H Bonds of Ammonia Induced by Triruthenium Polyhydrido Clusters : Ruthenium polyhydrido cluster (Cp^*Ru)_3H_5 reacted with ammonia to produce a mono-μ_3imido complex and dihydrogen as a result of activation of the two N-H bonds. The N-H bond cleavage was accelerated in the reaction with a proxo complex, (Cp^*Ru)_3(μ-O)(μ-H)_3. Less
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