Ruthenium chemical characterization

Bedja L, Hotchandani S. and Kamat P. V. (1994), Preparation and photoelectro-chemical characterization of thin Sn02 nanocrystalline semiconductor films and their sensitization with bis(2,2 -bipyridine)(2,2 -bipyridine-4,4 -diearboxylie aeid) ruthenium(II) eomplex , J. Phys. Chem. 98,4133 140. 

The steps and missteps in the process of discovering new elements led to caution in accepting a previously unidentified spectroscopic feature as evidence for a new element (Boyd 1959). Chemical characterization was required. For example, masurium was proposed for element 43, and illium and fiorentium were proposed for element 61 based on atomic spectroscopy of extracts from minerals. In retrospect, it is clear that there was evidence for unusual conditions for these elements. For example, above 7N the only mass numbers of stable isotopes of elements with odd atomic number are also odd, and there is only one stable isobar for each odd A. Molybdenum (Mo) has stable isotopes 92, 94—98, and 100. Ruthenium has 96, 98-102, and 104. Niobium has 93, and rhodium 103. Nothing is left for technetium, which would have the best chance for stability at mass numbers 97 and 99. Similarly, either neodymium or samarium has a 3-stable isotope fi om 142 to 150 nothing is left for promethium. 

For ES development, XPS is usually used to examine the oxidation states of different pseudocapacitive materials. A study of this use examined the oxidation states of ruthenium oxide powders with various water contents [38,39]. XPS is also used to study electrode functionalization through elemental analysis. For example, it can be used to investigate and improve the concentrations and types of nitrogen groups created by doping graphene and CNTs by various procedures. XPS also provides chemical characterization analysis for advanced electrolytes [40,41]. All these data help researchers determine the correlation between chemical structures and the capacitive characteristics of materials. 

Imamura (11,20,21) synthesized several similar perpendicular dimers exploiting axial coordination of the 4-pyridyl free-base porphyrin to Ru(II)CO (3) and Os(II)CO (4) porphyrins (Fig. 1). The pyridine-ruthenium and pyridine-osmium interactions are much stronger than the pyridine-zinc interaction, and the complexes are perfectly stable in solution and can be isolated by precipitation. One of the ruthenium dimers was characterized by FAB-MS (11). Complexation is accompanied by characteristic changes in JH NMR chemical shift, indicating... 

A complete description of the synthetic methodology and the characterization of the obtained metallosupramolecular block copolymers was reported in a recent paper [324]. These compounds have been referred to as metallosupramolecular block copolymers and designated by the acronym Ax-[Ru]-By, where A and B are the two different polymer blocks, -[Ru]- denotes the fczs-2,2/ 6/,2/terpyridine-ruthenium(II) linkage between the A and B blocks, and x and y represent the average degree of polymerization of the A and B blocks, respectively. The chemical structure of a PEB-[Ru]-PEO metallosupramolecular copolymer is depicted in Fig. 23. 

The chemical structure of the polymers was confirmed by NMR and elemental analysis, and spectroscopically characterized in comparison with monodisperse low molecular weight model compounds. Scheme 5 outlines the approach to the model compounds. Model compounds 31-34 were synthesized by complexation of the ruthenium-free model ligands 29/30 with 3/4. The model ligands were synthesized in toluene/diisopropylamine, in a similar fashion as the polycondensation using Pd(PPh3)4 and Cul as catalyst (Sonogashira reaction) [34,47-49]. 

The platinum-group metals (PGMs), which consist of six elements in Groups 8— 10 (VIII) of the Periodic Table, are often found collectively in nature. They are ruthenium, Ru rhodium, Rh and palladium, Pd, atomic numbers 44 to 46, and osmium, Os iridium, Ir and platinum, Pt, atomic numbers 76 to 78. Corresponding members of each triad have similar properties, eg, palladium and platinum are both ductile metals and form active catalysts. Rhodium and iridium are both characterized by resistance to oxidation and chemical attack (see Platinum-group metals, compounds). 

The reactions are catalyzed by transition metals (cobalt, iron, and ruthenium) on high-surface-area silica, alumina, or zeolite supports. However, the exact chemical identity of the catalysts is unknown, and their characterization presents challenges as these transformations are carried out under very harsh reaction conditions. Typically, the Fischer-Tropsch process is operated in the temperature range of 150°C-300°C and in the pressure range of one to several tens of atmospheres [66], Thus, the entire process is costly and inefficient and even produces waste [67]. Hence, development of more economical and sustainable strategies for the gas-to-liquid conversion of methane is highly desirable. 

A special issue devoted to molecular machines appeared in Accounts of Chemical Research in 2001. It reflects the current interest for this field in which ruthenium complexes act as important tools. Molecular machines are characterized by a mobile part and a stationary part. Photochemical and electrochemical inputs can make a machine work, offering the advantage of being switched on and off easily and rapidly. Mechanically interlocked molecules, such as rotaxanes and catenanes, are suitable candidates. Crown ethers, cyclophanes, and calixarenes are representative families of the cyclic... 

The only selenocyanate-containing complex of ruthenium or osmium is believed to be [Ru(NH3)5SeCN](C104)2 which was characterized by comparing the UV data with expected band positions from the spectro-chemical series 490). 

To clarify the mechanism of propylene adsorption on Ru-Co clusters the quantum-chemical calculation of interaction between it and Ru-Co, Ru-Ru, and Co-Co clusters were carried out. During the calculation it was assumed that carbon atoms of C-C bond are situated parallel to metal-metal bond. The distance at which the cluster and absorbable molecule begin to interact is characterized by the nature of active center. Full optimization of C3H6 molecule geometry confirms that propylene adsorbs associatively on Co-Co cluster and forms Jt-type complex. In other cases the dissociate adsorption of propylene is occurred. The presence of Ru atom provides significant electron density transfer from olefin molecule orbitals to d-orbitals of ruthenium in bimetallic Ru-Co- or monometallic Ru-Ru-clasters (independently on either the tertiary carbon atom is located on ruthenium or cobalt atom.). At the same time the olefin C-C bond loosens substantially down to their break. 

The combined information obtained by the different characterization methods applied allows the conclusion that deposits of ruthenium oxide at BDD, ranging from approximately one hundredth of a monolayer, maintain the physicochemical properties of RUO2, which proves the very limited degree of chemical interaction with the support. The deposits are most probably organized in nanoparticles growing around nucleation sites. When particles and clusters of particles reach a size of 50-60 nm, their charge-storage and catalytic behavior closely resembles that of thick oxide films. 

General Chemical and Physical Characterization. The x-ray diffraction data, chemical analyses by x-ray fluorescence and the effects of various synthesis parameters explored in this study lead to the conclusion that a new series of pyrochlores represented by formula 1 has been synthesized. The substitution of the larger post transition element cation for the noble metal cation on the octahedrally coordinated B-site leads to a considerable enlargement of the pyrochlore s cubic unit cell dimension. The relationship between lattice parameter (ag) and extent of substitution of ruthenium by either lead or bismuth is linear as shown in Figure 1. 

Ruthenium-copper aggregates of the type described have been studied with chemical and physical probes. Chemical probes that have been very informative include hydrogen chemisorption and the hydrogenolysis of ethane to methane. Physical probes useful in these characterizations include X-ray diffraction and electron spectroscopy. 

When the initial research on bimetallic clusters such as ruthenium-copper and osmium-copper was conducted, the characterization of the clusters was limited to methods involving chemical probes because of the difficulty of obtaining information with physical probes. In recent years, however, advances in X-ray absorption spectroscopy have changed the situation markedly. In particular, improvements in methods of obtaining extended X-ray absorption fine structure (EXAFS) data with the use of synchrotron radiation (13), in conjunction with advances in methods of data analysis (14), have made EXAFS a valuable tool for obtaining structural information on bimetallic clusters. 

Kim, I.H., J.H. Kim, Y.H. Lee, and K.B. Kim, Synthesis and characterization of electro-chemically prepared ruthenium oxide on carbon nanotube film substrate for supercapacitor applications. Journal of the Electrochemical Society, 2005. 152(11) pp. A2170-A2178 Kim, I.H., J.H. Kim, and K.B. Kim, Electrochemical characterization of electrochemically prepared ruthenium oxide/carbon nanotube electrode for supercapacitor application. Electrochemical and Solid State Letters, 2005. 8(7) pp. A369-A372... 

Park, S., A. Wieckowski, and M.J. Weaver, Electrochemical infrared characterization of CO domains on ruthenium-decorated platinum nanoparticles. Journal of the American Chemical Society, 2003. 125(8) pp. 2282-2290... 

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... 

Figure 3. Summary of the mechanism of the overall catalytic cycle. The ruthenium complexes within solid boxes have been isolated and fully characterized. Those within dashed boxes have been observed, but neither fully characterized nor isolated. The identity of the two ligands, labeled L, in the precursor to 3 remains obscure. The hydroxymethoxycarbene has not been observed. (Reproduced with permission from ref. 19. Copyright 1994 American Chemical Society).

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