Ruthenium thermolysis

In the iron, ruthenium, and osmium derivatives, there are eases of r] re-switeh on thermolysis followed by the elimination of small ligands. Organo-ruthenium speeies eontaining pyrazol-l-ylborate or -methane ligands with bulky substituents often have uneoordinated pyrazol-l-yl moieties and agostie R—B(C) - - - M interaetion. The latter sometimes influenees the properties of the jj -eoordinated speeies as well. 

Thermolysis of ruthenium carbene complexes leads to intramolecular r/> -bcnzylic C-H functionalization in the presence of a hydrogen-accepting olefin (Equation (35)).44,44a. 

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],... 

Thermolysis of RuPh2(TPP) at 100 °C for 30 h in benzene produces a phenyl-ruthenium(III) complex, RuPh(TPP) [155] (see Table 2). In contrast to RuPh2(P) and FePh(P) [222] no N-arylation occurred on oxidation of the five-coordinate RuPh(P) [306]. 

Thermolysis of ruthenium vinyl complexes also promotes intramolecular orthometallation [Eq. (112)]. However, performing the reaction in the... 

Similarly, thermolysis of the triosmium NHC cluster Os3(ImMe2)(CO)n affords the edge-bridged (24, M — Os) and derivatives (21, M = Os), resulting from sequential oxidative addition of one and two C-H bonds, respectively the ruthenium analogue 21 is prepared from a similar reaction, which affords as minor products the pentanuclear clusters 25 and 26 containing p4-q2-CO ligands.29... 

The abnormal carbene complex 27 (bonded through C3) is formed from the reaction between M3(CO)i2 (M = Ru, Os) and the bulky NHC ImAd2 (l,3-di(adamantyl)imidazol-2-ylidene) the reaction with the ruthenium precursor occurs readily in thf at room temperature, whereas the osmium reaction requires heating at 70 °C. Thermolysis of 27 affords 28.30... 

Ruthenium clusters with even higher nuclearity have also been isolated. When (1) is refluxed in ethanol for 18h, the hexaruthenium hydrido complexes [HRu6(CO)i8] (18) and [H2Ruio(CO)25] (19) are produced, along with metallic ruthenium (equation 8). The dihydride complex (19) represents the first noncarbido decaruthenium cluster. A trianion with 11 ruthenium centers (20) is synthesized by thermolysis of (1) in undried acetonitrile (equation 9), and... 

Certain transition-metal salts were also found to catalyze the apparent 1,6-ECRC. For example, thermolysis of silyl ether 74 (R1 = R2 = H) in toluene solution at 110°C (7 d) affords only a modest yield of enone 76. Attempts to cyclize the potassium enolate corresponding to 74 were also unsuccessful. However, treatment of 74 with substoichiometric amounts of a palladium(II) complex, bis(trifurany]phosphane)palladium dichloride [Pd(PFu3)2Cl ], in toluene (110 °C, 72 h) affords enone 76 in 84% yield. Substitution at R1 is detrimental, but butyl and phenyl substituents at R2 afford -substituted 76 in comparable yields. (Triphenylphos-phane)ruthenium dichloride [Ru(PPh3)Cl2] can be used in place of the palladium salt. 

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