Ruthenium, as catalyst for

The Action of Rhodium and Ruthenium as Catalysts for Liquid-Phase Hydrogenation... 

Fuel cells essentially reverse the electrolytic process. Two separated platinum electrodes immersed in an electrolyte generate a voltage when hydrogen is passed over one and oxygen over the other (forming H30+ and OH-, respectively). Ruthenium complexes are used as catalysts for the electrolytic breakdown of water using solar energy (section 1.8.1). 

Many late transition metals such as Pd, Pt, Ru, Rh, and Ir can be used as catalysts for steam reforming, but nickel-based catalysts are, economically, the most feasible. More reactive metals such as iron and cobalt are in principle active but they oxidize easily under process conditions. Ruthenium, rhodium and other noble metals are more active than nickel, but are less attractive due to their costs. A typical catalyst consists of relatively large Ni particles dispersed on an AI2O3 or an AlMg04 spinel. The active metal area is relatively low, of the order of only a few m g . ... 

WO 2009/124853 Al, F Hoffmann-La Roche AG New ruthenium complexes as catalysts for metathesis reactions... 

Besides ruthenium porphyrins (vide supra), several other ruthenium complexes were used as catalysts for asymmetric epoxidation and showed unique features 114,115 though enantioselectivity is moderate, some reactions are stereospecific and treats-olefins are better substrates for the epoxidation than are m-olcfins (Scheme 20).115 Epoxidation of conjugated olefins with the Ru (salen) (37) as catalyst was also found to proceed stereospecifically, with high enantioselectivity under photo-irradiation, irrespective of the olefmic substitution pattern (Scheme 21).116-118 Complex (37) itself is coordinatively saturated and catalytically inactive, but photo-irradiation promotes the dissociation of the apical nitrosyl ligand and makes the complex catalytically active. The wide scope of this epoxidation has been attributed to the unique structure of (37). Its salen ligand adopts a deeply folded and distorted conformation that allows the approach of an olefin of any substitution pattern to the intermediary oxo-Ru species.118 2,6-Dichloropyridine IV-oxide (DCPO) and tetramethylpyrazine /V. V -dioxide68 (TMPO) are oxidants of choice for this epoxidation. 

Although salen complexes of chromium, nickel, iron, ruthenium, cobalt, and manganese ions are known to serve as catalysts for epoxidation of simple olefins, the cationic Mn-salen complex is the most efficient. 

Rhodium(I) and ruthenium(II) complexes containing NHCs with hemilabile ether moieties were successfully applied as catalysts for the cyclopropanation of olefins with diazoalkanes [Eq. (53)]. ... 

There is increased interest in the use of Ru-based systems as catalysts for oxygen reduction in acidic media, because these systems have potential applications in practicable direct methanol fuel cell systems. The thermolysis of Ru3(CO)i2 has been studied to tailor the preparation of such materials [123-125]. The decarbon-ylation of carbon-supported catalysts prepared from Ru3(CO)i2 and W(CO)6, Mo(CO)is or Rh(CO)is in the presence of selenium has allowed the preparation of catalysts with enhanced activity towards oxygen reduction, when compared with the monometallic ruthenium-based catalyst [126],... 

This book is concerned with the application of ruthenium complexes as catalysts for useful organic oxidations. 

Quite recently, some mononuclear ruthenium complexes such as [(p-cymene)RuX-(CO)(PR3)]OTf (X = Cl, OTf, R = Ph, Cy) have been found to work as catalysts for the propargylation of aromatic compounds such as furans, where some ruthenium complexes were isolated as catalytically active species from the stoichiometric reactions of propargylic alcohols (Scheme 7.27) [31]. The produced active species promoted the propargylation of furans vdth propargylic alcohols bearing not only a terminal alkyne moiety but also an internal alkyne moiety, indicating that this propargylation does not proceed via allenylidene complexes as key intermediates. 

Levy et al.5 and Kaufman and Sen3 investigated cobalt and nickel borides as catalysts for controlled generation of H2 from NaBH, solutions. Brown and Brown6 investigated various metal salts and found that ruthenium and rhodium salts liberated H2 most rapidly from borohydride solutions. These results, along with our own work, indicated that ruthenium would most likely be the most active metal for catalysis of... 

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