Ruthenium trimetallic complexes

Dewhurst et al have reported the fluoride-mediated protodesilylation of silylated propargylidynes in the presence of rhodium, ruthenium,iridium, " gold and mercury complexes to provide a range of C3-spanned heterobi- and trimetallic complexes. 

Also, bi- and trimetallic cumulene complexes, such as M=C=M, M=M=C, M=M=M and M=C=C=M are known. Cationic ruthenium allenylidene complexes are used as catalysts for ring closing metathesis reactions. Nonlinear optical properties have been measured for the Group 6 cumulenylidene complexes. Also, cationic chromium or iron vinylidene complexes undergo [2-1-2] cycloaddition reactions across imines to give fi-lactams. This reaction is useful for the synthesis of j8-lactam antibiotics. ... 

The trimetallic complexes coupling two ruthenium or osmium LAs to a central rhodium absorb efficiently throughout the UV and visible regions of the... 

In analogous fashion, the ruthenium- or iridium-based bimetallic and trimetallic CTV complexes such as 54-57 also make excellent anion hosts. The CTV cavity, however, is wider and more shallow and hence, the BF anion is too small to be effectively bound. This is evidenced by the crystal structures of the BF J salts of 56 and the iridium analogue 57 in which the anion within the cavity is either extremely disordered or is situated to one side of the cavity. We have found that host 54 exhibits a pronounced selectivity for TcO in nonaqueous solutions, presumably as a consequence of the wide cavity in conjunction with the larger anion size.104,109 Indeed, the X-ray crystal structure of the mixed ReO CFjSOj salt shows the... 

One approach for achieving multiphoton and multielectron reactions is to synthesize cluster complexes where the metal centers are in close conununication. One of the simplest bridging species that can be used to link two Ru(bpy)2 -type centers in close proximity to achieve this goal is a cyanide ion. The ruthenium(II) bimetallics NC-Ru(bpy)2-CN-Ru(bpy)2-CN , NC-Ru(bpy)2-Ru(phen)2-CN, and the trimetallic NC-Ru(bpy)2 N-Ru(bpy)2-NC-Ru(bpy)2-CN have been synthesized, and each shows a shift of the emission band to low energy as compared to the monomeric complex Ru(bpy)2(CN)2. This lowest d-n triplet excited... 

Although mechanistic details are still unclear, an open-form triruthenium complex 43, which adopted a ruthena-benzene structure, was derived from the bimetallic 1,4-cyclohexadiene complex 42 (Equation (14)). On the basis of the fact that complex 43 was dicationic, the trimetallic skeleton is most likely formed by the reaction of 42 with a cationic monometallic species, [Cp Ru], generated by the partial decomposition of 42. The X-ray diffraction study of 43 showed that the central ruthenabenzene moiety was coordinated to one of the peripheral ruthenium atoms in an 7 -fashion and to the other in an 7 -fashion. This nonsymmetrical structure arises from the hydrido ligand bridging on one of the Ru-Ru bonds. 

The interatomic distance between the ruthenium atoms was lengthened to ca. 4 A by the insertion of diazocyclopentadiene into an Ru-Ru bond. When the reaction was carried out using an equimolar amount of diazocyclopentadiene, formation of an intermediate 105, in which only one of the Ru-Ru bonds was cleaved, was observed. A similar triruthenium complex was prepared by using diazoindene. In this case, coupling between the two 77 -indenyl moieties also took place, and trimetallic cluster 107 adopting an open-form structure was obtained as a byproduct. 

Comparisons of the spectroscopic and electrochemical properties of [(NH3)5RuNCFcCNRu(HN3)s] and [(NH3)5RuNCFcCNf where Fc is ferrocene, leads to the conclusions that the two ruthenium chromophores in the trimetallic ion do not interact strongly. This allows differences in the IT transition energies of the mixed-valence complexes to be ascribed to differences in charge distribution, in good agreement with theory. 

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