Ruthenate synthesis

Increasing the temperature of synthesis results in enhanced crystallinity as would be anticipated because of improved reaction kinetics. However, this observation is also consistent with a crystallization mechanism involving solubility. Furthermore, as the temperature increases so does the equilibrium concentration of lead in solution thus with all else held constant, increased temperature of reaction results in a smaller lattice parameter for the product lead ruthenate pyrochlore. 

One additional parameter that affects the solubility of lead ruthenate pyrochlores in alkali is the extent of lead substitution on the B-site. The greater the substitution (i.e. the larger x is in formula 1), the higher the solubility of the pyrochlores is in alkali 2). If it is assumed that a solution-reprecipitation mechanism of synthesis is operative, the stoichiometry-dependent solubility could explain why it becomes significantly more difficult to crystallize lead ruthenate directly out of alkaline solution when x <0.3. 

Synthesis of the bismuth-substituted bismuth ruthenates is, in most respects, similar to that of the lead ruthenate series. Precipitation/crystallization is effected in a relatively oxidizing. 

Figure 9 illustrates the O2 electroreduction activity of a number of lead ruthenate pyrochlores, Pb2(Ru2-xPbx)06.5> here 0 < x < 1.0. These data demonstrate that catalysts of roughly equivalent activity can be synthesized over the entire compositional range. In two examples where the activity was noticeably lower (x = 0.04 and x 0.98), the synthesis conditions were such that the surface areas of... 

A particularly satisfactory ruthenium catalyst was prepared as follows. Commercial ruthenium powder was fused with a mixture of potassium hydroxide and potassium nitrate (1 part ruthenium, 10 parts potassium hydroxide, 1 part potassium nitrate) preferably in a silver crucible and stirred with a silver spatula. Pusion was complete after 1 to 2 hours. After cooling, the fused mass was dissolved in water a deep red solution of potassium ruthenate resulted, which was heated to boiling. Methyl alcohol was added dropwise to the boiling solution. The reduction of potassium ruthenate to ruthenium dioxide began with the addition of the first drops and went rapidly to completion. The precipitate settled after a few hours. It was washed on a fritted glass plate, first with water acidified with nitric acid and then with distilled water. Finally the catalyst was dried at 110°C. The reduction to metal proceeds just as smoothly under synthesis conditions as by a hydrogen treatment, which latter is usually required with catalysts of the iron group. 

The exact nature of the complex [Ru(Pc)Cl] remains unknown. Formulations of a ruthen-ium(III) complex with axial Cl , [Ru(Pc)Cl], or a ruthenium(II) species with chlorinated Pc, [Ru(ClPc)], "" have been proposed, although H, C NMR and electronic spectral data appear to show no evidence for chlorination at the Pc ring. " The complexes [Ru(ClPc)L2] (L = PPh, py, methyl imidazole, P(OBu")3, P(Bu")3) have been reported. " "" The synthesis of [Ru Pc-(S03)4 ]" (H2PC-SO3H = phthalocyanine tetrasulfonic acid) has been mentioned. ... 

Fukuda K, Saida T, Sato J, Yonezawa M, Takasu Y, Sugimoto W (2010) Synthesis of nanosheet crystallites of ruthenate with an alpha-NaFe02-related structiffe and its electrochemical supercapacitor property. Inorg Chem 49 4391-4393... 

Preparation of ammonia synthesis catalysts by the one-step impregnation of a stable potassium ruthenate solution onto a graphite support. L. Bretherick and S. R. Tennison (British Petroleum Ltd). GB 2034194 (1983). 

In the 1970s and 1980s, it was discovered that electron-deficient alkenes, such as tetracyanoethylene (TCNE, 55) reacted with metallated alkynes 54 to furnish a metallated hexasubstituted 1,3-diene unit 56, an overall transformation akin to enyne metathesis (Scheme 1.8) [37, 39]. In a recent (2012) addition to this work, the Bruce group reported the synthesis of a ruthenated [3]dendralene 58 via insertion of phenylacetylene (57) into 56 (Scheme 1.8) [38]. The metallated dendralene synthesis is low yielding and, as yet, an isolated example, but presents an interesting avenue for future investigations. 

The synthesis and characterization of K3[Ru(CN)5(dmso)] have been reported. Kinetics of formation of, and substitution in, this pentacyano-ruthenate(II) anion are all consistent with dissociative interchange. Some longstanding uncertainties in relation to the solution chemistry of hexacyanoruthenates have been resolved. The ruthenium(II) complex can be oxidized by air in dimethylformamide solution (but not in aqueous media) to [Ru (CN)g] the latter decomposes back to ruthenium(II) in water, even when this has been fully purged with nitrogen. ... 

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