Ruthenium selenium containing

In contrast to sulfur (Section 45.7), relatively little has been published on ruthenium complexes containing selenium and tellurium ligands. 

The oxidation potential represents the ability of a metal atom (M) to be ionized to an ion (M" ") with loss of an electron. For the oxidation of organic molecules, transition metal compounds containing chromium, manganese, ruthenium, selenium, silver, or cerium are often used. The oxidation potential is therefore a useful method for examining the oxidizing power of these reagents. 

Transition metal surfaces enriched with S, Se and Te, have been considered as candidates for DAFC cathode catalysts [112-115], For example, ruthenium selenium (RuSe) is a weU-studied electro-catalyst for the ORR [116, 117]. The ORR catalysis on pure Ru surfaces depends on the formation of a Ru oxide-like phase [118]. Ru is also an active catalyst for methanol oxidation. On the other hand, the activity of the ORR on RuSe is found not be affected by methanol [116]. RuS, has also been reported insensitive to methanol [119-122], DPT studies of model transition metal surfaces have provided with atomistic insights into different classes of reactions relevant to fuel cells operation, such as the hydrogen evolution [123], the oxygen reduction [124], and the methanol oxidation [125] reaction. Tritsaris, et al. [126] recently used DPT calculatimis to study the ORR and methanol activation on selenium and sulfur-containing transition metal surfaces of Ru, Rh, Ir, Pd, Co and W (Fig. 8.9). With RuSe as a starting point, the authors studied the effect of the Se on... 

Most studies reported on ruthenium chalcogenides containing Se, S, and Te relate, so far, to the acid medium. It is, however, interesting to compare some feamres from the cyclic voltammetry results generated in acid as well as in alkaline media for the metal core as well as the selenium coordinated to the metallic core (Fig. 14.11). 

Diarylacetylenes are converted in 55-90% yields into a-diketones by refluxing for 2-7 h with thallium trinitrate in glyme solutions containing perchloric acid [413. Other oxidants capable of achieving the same oxidation are ozone [84], selenium dioxide [509], zinc dichromate [660], molybdenum peroxo complex with HMPA [534], potassium permanganate in buffered solutions [848, 856, 864,1117], zinc permanganate [898], osmium tetroxide with potassium chlorate [717], ruthenium tetroxide and sodium hypochlorite or periodate [938], dimethyl sulfoxide and iV-bromosuccin-imide [997], and iodosobenzene in the presence of a ruthenium catalyst [787] (equation 143). 

Aue WA and Singh H (2001) Chemiluminescent photon yields measured in the flame photometric detector on chromatographic peaks containing sulfur, phosphorus, manganese, ruthenium, iron or selenium. Spectrochimica Acta Part B 56 517-525. 

The general formula RuSe describes rathenium particles that are modified by a small amount of selenium the optimum activity is achieved for x 0.1. As obtained from anomalous small angle X-ray scattering (ASAXS) measurements, ruthenium forms almost spherical nanoparticles from which the selenium content is deposited onto the surface. The typical size of the rathenium particles is around 2.5 mn selenium forms small clusters on the surface with a diameter <0.6 nm. A mixing of the two components has not been observed. From extended X-ray absorption fine structure (EXAFS) analysis an oxygen-free selenium structure and oxygen-containing species on the uncovered rathenium surface... 

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