Ruthenium bimetallic complexes

An example of particular interest is the two-fold introduction of M(CO)n moieties at silicon to give HMPA adducts of organometallic analogues of silaallene. It has been shown that this reaction proceeds through the dichlorosilylene complex as intermediate. Both the iron 22 and ruthenium 23 compound and also the bimetallic complex 24 are accessible. 

Hsu et al. [15] applied a bimetallic catalyst comprising rhodium and ruthenium for the hydrogenation to combine the high selectivity of the rhodium complex with the lower cost of the ruthenium complex. When the amount of each metal is identical, the catalytic activity of the bimetallic complex catalyst system was similar to that of the single rhodium-complex catalyst, containing... 

The reactivity of osmium with terminal alkynes can be used to prepare bimetallic complexes. When an osmium hydride reacts with a terminal aUcyne that is part of a ruthenium complex, the product is a Ru-Os bimetallic complex with a hydrocarbon bridge (Scheme 16). Another bimetallic complex, [Cp(PPh3 )20s=C=C=CH-C=C-0s(PPh3)2Cp]+, resulted from the reaction between [CpOs(PPh3)2]+ with HC=CCH(OH)C=CH followed by alumina. The unsaturated C5 bridging group is V-shaped. 

Methanol homologation using carbon dioxide catalyzed by ruthenium-cobalt bimetallic complex system... 

The ruthenium-cobalt bimetallic complex system catalyzes the homologation of methanol with carbon dioxide and hydrogen in the presence of iodide salts. A synergistic effect is found between these two metals. The yield of ethanol is also affected by the Lewis acidity of the iodide salt, lithium iodide being most effective. The reaction profile shows that methanol is homologated with CO formed by the hydrogenation of CO2. 

Ruthenium-cobalt bimetallic complex catalyzed methanol homologation with CO2 ... 

There are two possible pathways to homologate methanol with carbon dioxide the CO2 insertion path and CO insertion path (Scheme 2). As for the former, Fukuoka et al. reported that the cobalt-ruthenium or nickel bimetallic complex catalyzed acetic acid formation from methyl iodide, carbon dioxide and hydrogen, in which carbon dioxide inserted into the carbon-metal bond to form acetate complex [7]. However, the contribution of this path is rather small because no acetic acid or its derivatives are detected in this reaction. Besides, the time course... 

HeterobimetalUc ruthenium alkylidenes, which may be prepared by reaction of ClaRuIPCyalafCHR) with [Ru(pactive initiators are the bimetallic complexes (p-cymene)RuCl(p-Cl)2RuCl(CHPh)(NHC) and (Cp )RhCl(p-Cl)2RuCl(CHPh)(NHC) (NHC=N-heterocyclic carbene, Cp =pentamefhylcyclopentadienyl) [236, 237]. 

The bimetallic complex [(OC)3Fe(/<-PPh2)2Ru(CO)3] is also an active catalyst for the homogeneous hydroformylation of styrene (393 K, 20 atm, CO/H2 = 1). A synergistic effect between iron and ruthenium was observed and the intact complex was recovered at the end of the reaction. ... 

Large polyaza cavity-shaped ligands 514 were designed by Thummel et al. One or two ruthenium or osmium metal complexes were hganded by 514. In the case of bimetallic complexation, limited communication between the two halves of the bridging ligand was observed (93IC1587). 

Recently, this methodology has been applied by Liu and co-workers to obtain bimetallic ruthenium Tp complexes with cr,cr -bridging azobenzene chains. ... 

It is useful to compare the molecular and electronic stmctures of the bis(imino)pyridine iron dinitrogen complexes with those of the ruthenium congeners reported by Berry and coworkers [32]. Stirring K -( PDI)Ru(q -arene) complexes in non-arene solvents under a dinitrogen atmosphere furnished the bimetallic ruthenium dinitrogen complex [( PDI)Ru]2(P2> l dimeric... 

Several well-documented examples of the oxidative addition of dihydrogen to bimetallic complexes to form dinuclear products are also known (e.g., Equation 6.11 ), but little definitive mechanistic work on tliese reactions has appeared. In each case, the addition of dihydrogen is thought to occur at a single metal site, such as the ruthenium in Equation 6.11, rather than simultaneously across two metals. One piece of evidence in support of this assertion is the absence of reactivity of dihydrogen toward bimetallic complexes that possess a metal-metal bond, but lack sites of coordinative unsaturation. For instance, (OC) Fe(p -AsMe2)Mn(CO) does not react with even 1,000 psi at 140 °C. ... 

For example, the formation of a ruthenium-ethylene complex was observed during the attempted preparation of a monophosphine bimetallic species by reaction of RuCl2(=CH2)(PCy3)2 (19) with [Ru(p-cymene)Cl2]2 [31, 37]. 

Quebatte, L., Solari, E., Scopelliti, R., Severin, K., A bimetallic ruthenium ethylene complex as a catalyst precursor for the Kharasch reaction, Organometallics 2005,24 1404-1406. 

This section is dedicated to a description of the chemistries of trinithenium and triosmium clusters that do not contain hydrocarbon ligands. This section should be viewed as an addition to the chemistry described in sections 32.5 and 33 of COMC (1982) and section 12 of COMC (1995) as most of the main themes have been developed in the previous two decades. Overall, the interest in the cluster chemistry of ruthenium and osmium during the period 1994-2004 has tended to focus mainly on higher nuclearity and mixed metal clusters in order to enhance the developments in catalysis and bridge the gap between molecular clusters and nanoparricles. However, triruthenium and triosmium clusters continue to play a pivotal role in the chemistry of ruthenium and osmium. Both classes of clusters can be, and are, used extensively as precursors for the synthesis of higher nuclearity clusters as well as the formation of mono- and bimetallic complexes. No up-to-date review of the chemistry of either Ru3(CO)i2 or Os3(CO)i2 and their compounds is available, but several annual reviews of the chemistry of mthenium and osmium, which include the chemistry of the trinuclear clusters, are available. ... 

Newcome and coworkers have reported the synthesis of a tetraarm complex containing two ruthenium coordination complexes in each branch. Polymer 91 was prepared by reaction of a core molecule containing four terpyridine units with 4 eq of a bimetallic complex containing a reactive ruthenium trichloride moiety. 

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