Ruthenium spectral properties

In a more detailed examination of the ruthenium-cobalt-iodide "melt" catalyst system, we have followed the generation of acetic acid and its acetate esters as a function of catalyst composition and certain operating parameters, and examined the spectral properties of these reaction products, particularly with regard to the presence of identifiable metal carbonyl species. 

In this context, it is particularly interesting to note that catalysis runs under the same conditions, but using H4Ru4(CO)i2 as the initial source, have activity indistinguishable from that of runs starting with Ru3(CO)i2. In addition, the spectral properties of the active solutions from these two sources are indistinguishable. Lastly it is also notable that comparable activity is seen with solutions prepared with ruthenium trichloride (RuCla nH20) as the initial ruthenium source. 

Data in Table V illustrate the production of acetic acid from 1/1 syngas. A variety of ruthenium-containing precursors - coupled with cobalt halide, carbonate and carbonyl compounds - at different initial Co/Ru atomic ratios, have been found to yield the desired carboxylic acid when dispersed in tetrabutylphosphonium bromide. In a more detailed examination of the ruthenium-cobalt-iodide melt catalyst system, we have followed the generation of acetic acid and its acetate esters as a function of catalyst composition and certain operating parameters, and examined the spectral properties of these reaction products, particularly with regard to the presence of identifiable metal carbonyl species. 

The effect of the electrochemical and hydrophobic properties of the reactants on the intramicellar charge separation rate constant for model systems of ruthenium-tris-bipyridile, tris-phenanthroline and tris-diphenylphenanthroline complex quenching by organic cations in SDS micelles was studied by Miyashita et al. [124,125]. The plot of vs. the free energy of the electron transfer reaction calculated from electrochemical and spectral properties of the reactant (Fig. 4) differs from the well-known Rehm-Weller and Marcus plots for homogeneous solutions. 

Very T, Despax S, Hebraud P, Monari A, Assfeld X (2012) Spectral properties of polypyridyl ruthenium complex intercalated in DNA theoretical insights on the surrounding effects for [Ru(dppz)(bpy)j2+. phys Chem Chem Phys 14 12496-12504... 

This is considerably different from the recombination reaction with, for example, typical ruthenium dyes. This slow re-reduction of the dyad is explained by the low redox potential of the osmium center, the value of 0.66 V (vs. SCE) observed, points to a small driving force for the redox process. This observation is important for the design of dyes for solar cell applications. Osmium compounds have very attractive absorption features, which cover a large part of the solar spectrum. However, their much less positive metal-based oxidation potentials will result in a less effective re-reduction of the dyes based on that metal and this will seriously affect the efficiency of solar cells. In addition, for many ruthenium-based dyes, the presence of low energy absorptions, desirable for spectral coverage, is often connected with low metal-based redox potentials. This intrinsically hinders the search for dyes which have a more complete coverage of the solar spectrum. Since electronic and electrochemical properties are very much related, a lowering of the LUMO-HOMO distance also leads to a less positive oxidation potential. 

Park, S., Y.T. Tong, A. Wieckowski, and M.J. Weaver, Infrared spectral comparison of electrochemical carbon monoxide adlayers formed by direct chemisorption and methanol dissociation on carbon-supported platinum nanoparticles. Langmuir, 2002.18(8) pp. 3233-3240 Park, S., Y. Tong, A. Wieckowski, and M.J. Weaver, Infrared reflection-absorption properties of platinum nanoparticle films on metal electrode substrates control of anomalous opticalejfects. Electrochemistry Communications, 2001. 3(9) pp. 509-513 Park, S., P.K. Babu, A. Wieckowski, and M.J. Weaver, Electrochemical infrared characterization of CO domains on ruthenium decorated platinum nanoparticles. Abstracts of Papers of the American Chemical Society, 2003. 225 pp. U619-U619... 

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