Triruthenium cluster

Summarized are a series of investigations using both thermal and photochemical techniques to probe the reaction dynamics of intermediates formed in various reactions of triruthenium cluster complexes. 

In this article we have summarized the use of both photochemical and more classical thermal kinetics techniques to deduce the nature of intermediates in the ambient temperature, fluid solution chemistry of several triruthenium clusters. In some cases the photochemically generated intermediates appear to be the same as those proposed to be formed along thermal reaction coordinates, while in other cases unique pathways are the results of electronic excitation. The use of pulse photolysis methodology allows direct observation, and the measurement of the reaction dynamics of such transients and provides quantitative evaluation of the absolute reactivities of these species. In some cases, detailed complementary information regarding... 

L = axial ligands, n = 0, 1, 2) have been extensively investigated regarding their specific electronic, chemical, and physical properties [4], Particularly, oxo-centered triruthenium cluster complexes with bridging acetates attracted the most attention owing to their synthetic accessibility, multiple redox behavior, intriguing mixed-valence chemistry, and versatile catalytic properties [5-7]. 

Layer-by-layer Ru3 cluster-based multilayers were fabricated onto preorganized self-assembled monolayer gold electrode surfaces by Abe et al. [15], in which [Ru3(q3-0)( i-0Ac)6(4,4/-bpy)2(C0)] was utilized as the synthetic precursor. The stepwise connection of oxo-centered triruthenium cluster units onto the gold electrode surface is a feasible approach for construction of Ru3 cluster-based oligomers on a solid surface, in which the bridging ligand 4,4 -bipyridine appears to mediate weak cluster-cluster electronic interaction between the Ru3 cluster centers. 

Fig. 1 Cyclic and differential voltammograms of PI12PC = CPPh2 (19 and 20) and trans-Ph2PCH = CHPPh2 (21) triruthenium cluster complexes recorded in 0.1 M dichloromethane solution of (Bu4N)(PF6). The scan rate is lOOmVs-1 for CV and 20mVs 1 for DPY...

The carbonylation of imidazole derivatives with several olefins takes place in high yields with the aid of an Ru3(CO)i2 catalyst.112,112a The carbonylation occurs exclusively at the a-position to the sp2 nitrogen (Equation (85)). A wide range of olefins can be utilized in this reaction, and a variety of functional groups are compatible under the reaction conditions. The (/i-H)triruthenium clusters such as 12 are proposed as a key species in this carbonylation reaction. Other five-membered A-heteroaromatic compounds, such as pyrazoles, oxazoles, and thiazoles, can be used for the carbonylation reactions, where the carbonylation takes place at the a-C-H bond to the sp2 nitrogen. 

The two water-soluble complexes Ru(PTA)Cl2(7/6-C10H14) and [RuC1(PTA)2( /6-CioHi4)]+ (PTA= l,3,5-triaza-7-phosphadamantane) (Fig. 16.1) have been tested as catalyst precursors for the hydrogenation of benzenes at 90 °C and 60 bar H2 [21]. After catalysis, the former complex was converted to a triruthenium cluster... 

The reaction of Ru3(CO)j2 with cyclododeca-l,5,9-trienes gives a mixture of triruthenium clusters and Ru4(CO)io(Ci2Hj6) which have been separated by chromatography3 . The X-ray structure of this tetraruthenium cyclododecatrienyl compound is shown in Fig. 17. 

These ligands often display unusual chemical behaviour not found, or rarely found, in mononuclear metal compounds. For example in [Ru3(CO)8(C8H6)J the triruthenium cluster stabilises pentalene(l), an organic molecule having only a transient existence under normal conditions, while in the complex... 

Metal cluster compounds of the carbonyl type have often served as catalyst precursors, that is, as the source of fragments that are the actual catalysts,18 although there have been relatively few fully detailed descriptions of catalytic cycles based on clusters.19 Triruthenium cluster compounds have been found to catalyze hydrogen... 

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