Ruthenium complexes mononuclear, synthesis

Although the above discussion is centered on the synthesis of polymeric osmium and ruthenium complexes, the methods employed are also very successful in the preparation of mononuclear complexes. In this context, the preparation of ruthenium or osmium complexes which are suitable for the formation of self-assembled monolayers (see Section 4.3 above) can be prepared by using the same approach. Starting from the precursor [M(bpy)2Cl2], one chloride atom can be replaced to yield complexes of the type [M(bpy)2Cl L]+, where L is the surface active ligand. In the presence of water, species of the type [M(bpy)2(L)2]2+ are obtained. 

Siebert and co-workers reported the reaction of 2,3-dihydro-l,3-diborolyl ligands with ruthenium complexes <1999EJI1685>. 2,3-Dihydro-17/-l,3-diborole derivatives 31a-d were treated with MeLi at -55 °C and then reacted with [(CsMes)RuCl]4 to give the violet mononuclear (7] -pentaalkyl-2,3-dihydro-l,3-diborolyl) 7 -penta-methylcyclopentadienyl)ruthenium complexes 32a-d (Equation 1). The synthesis of (77 -pentaalkyl-2,3-dihydro-... 

Although ruthenium is significantly less expensive than rhodium and although its use has been recommended since 1960 (7) for the oxo synthesis, complexes of this metal have not been developed as catalysts. However, many papers and patents have referred to the results obtained employing various ruthenium complexes. The purpose of this article is to analyze the work done involving ruthenium compounds, restricting the scope only to the hydroformylation reaction and not to the carbonylation reaction, which would demand to too lengthy an article. In this review we examine successively mononuclear ruthenium complexes, ruthenium clusters as precursors, photochemical activation, and supported catalysis. 

Dehydration of propargyl alcohols occurs commonly on mononuclear ruthenium complexes.[ l Water is formed from the terminal alkynic hydrogen and by the alcoholic OH this is the more common dehydration process (it is denoted Route A). These reactions afford organic intermediates leading to cumulene complexes useful for the synthesis of doped polyacetylenes or of non-linear optic materials. Dehydration of rhodium-coordinated propargyl alcohols " leads to free or coordinated cumulenes and can be catalyzed by alumina and chloride ions, Fig. 16. 

More recently and following the above procedure Elsenbaumer and coworkers reported the synthesis of homochiral multinuclear ruthenium complexes from oligomeric benzimidazoles as bridging ligands and enantiopure mononuclear [Ru(bpy)2(py)2] " (5.96) as a building blockJ ... 

The authors proposed a structural catalyst model based on the assumption of polymeric bonding of ruthenium metal clusters through the formation of ruthenium-aromatic ring bonds [259]. The validity of this contention was confirmed by synthesis of ruthenium complexes based on poly-1-vinylnaphthalene instead of polystyrene. It was demonstrated that both catalytic ruthenium-containing systems are active in the hydrogenation of unsaturated bonds in olefins, mononuclear aromatic hydrocarbons,... 

Finally, the surface-mediated synthesis of ruthenium carbonyl complexes has also been used to prepare supported ruthenium particles. Using silica as a reaction medium and conventional salts, apart from Ru3(CO)i2, mononuclear Ru(CO)j, and high nuclearity carbonyl-derived species can be obtained by CO reductive carbonylation [127, 128]. This opens new routes to preparing tailored supported ruthenium particles. 

Simple derivatives such as (p-cymene)OsCl2(DMSO) have been reported and the substitution chemistry of [(arene)RuL3l2+ complexes explored. The synthesis of cyclophane ruthenium sandwich complexes has been achieved to give mononuclear and triple-decker-sandwich complexes(52). 

This catalyst is also very efficient to perform the addition of bulky acids to simple alkynes as shown in the synthesis of the ferrocenylcarboxyhc styryl ester [73]. The mononuclear bis(carboxylate)ruthenium(ll) complex cis-[Ru(OAc)2(PPh3)2] has also shown good catalytic activity for the addition of carboxyhc acids to propargyhc... 

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