Rhenium ion

Ortho Esters and Di a Ik oxyca rhenium Ions Reactivity, Stability, Structure, and New Synthetic Applications. Pindur, U. Mtiller, J. Flo, C Witzel, H. Chem. Soc. Rev, 1987, 16, 75. 

Based on TPR results it can be concluded that intimate contact between rhenium and platinum is provided in bimetallic alloy particles on the surface of alumina supported catalysts. Therefore, one can expect that the oxidation of the catalyst followed by reduction at moderate temperature result in the formation of platinum and/or Re-Pt metallic nanoclusters and rhenium ions in atomic closeness. 

Rhenium ions, and especially tricarbonylrhenium(l)chloro fragments, have been used to organize and link pyridine-functionalized porphyrins as molecular squares, rectangles, planar dimers, and more complex structures. 

Considerable potential is associated with the catalytic applications of Ag NPs, and there are several reports on the research in this field. The oxidation of ethylene, catalyzed by polyacrylic acid (PAA)-Ag nanoclusters, was performed in glycol under 1 atm of ethyleneioxygen. Products were identified as ethylene oxide by analysis with gas chromatography. Ag nanoclusters thus prepared had higher catalytic activity than a commercial silver catalyst. The oxidation rate catalyzed by the PAA-Ag nanoclusters remarkably inaeased with inaeasing reaction temperature. PAA-protected Ag nanoclusters had much higher activity than poly(A-vinyl-2-pyrrolidone)-protected particles at high temperatures. The addition of both caesium and rhenium ions eminently increased the catalytic activity of PAA-Ag nanoclusters (Shiraishi and Toshima 2000, Toshima et al. 2001). 

MANGANESE, TECHNETIUM AND RHENIUM IONS IN AQUEOUS SOLUTIONS... 

Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (Vll) will exist as the pertechnetate ion, TcOr-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and cone, sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at IIK and below. 

Tantalum is a gray, heavy, and very hard metal. When pure, it is ductile and can be drawn into fine wire, which is used as a filament for evaporating metals such as aluminum. Tantalum is almost completely immune to chemical attack at temperatures below ISOoC, and is attacked only by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide. Alkalis attack it only slowly. At high temperatures, tantalum becomes much more reactive. The element has a melting point exceeded only by tungsten and rhenium. Tantalum is used to make a variety... 

It is widely used as filaments for mass spectrographs and ion gauges. Rhenium-molybdenum alloys are superconductive at 10 K. 

Precise measurement of isotope ratios can be obtained by comparing the yields of isotopic ions desorbing from a sample placed on a strongly heated filament that is generally made from platinum, tantalum, rhenium, or tungsten. 

Since detailed chemical structure information is not usually required from isotope ratio measurements, it is possible to vaporize samples by simply pyrolyzing them. For this purpose, the sample can be placed on a tungsten, rhenium, or platinum wire and heated strongly in vacuum by passing an electric current through the wire. This is thermal or surface ionization (TI). Alternatively, a small electric furnace can be used when removal of solvent from a dilute solution is desirable before vaporization of residual solute. Again, a wide variety of mass analyzers can be used to measure m/z values of atomic ions and their relative abundances. 

Occurrence of rhenium and molybdenum together in nature is a consequence of the similarities of these elements. Both elements have a high affinity for sulfide ion. Moreover, the radii of Re" " and Mo" ", 0.74 nm and 0.70 nm, respectively, ate almost identical, so that ReS2 [12038-63-0] and M0S2 have similar crystal stmctures with almost identical dimensions (see Molybdenumcompounds). 

Purely parallel reactions are e.g. competitive reactions which are frequently carried out purposefully, with the aim of estimating relative reactivities of reactants these will be discussed elsewhere (Section IV.E). Several kinetic studies have been made of noncompetitive parallel reactions. The examples may be parallel formation of benzene and methylcyclo-pentane by simultaneous dehydrogenation and isomerization of cyclohexane on rhenium-paladium or on platinum catalysts on suitable supports (88, 89), parallel formation of mesityl oxide, acetone, and phorone from diacetone alcohol on an acidic ion exchanger (41), disproportionation of amines on alumina, accompanied by olefin-forming elimination (20), dehydrogenation of butane coupled with hydrogenation of ethylene or propylene on a chromia-alumina catalyst (24), or parallel formation of ethyl-, methylethyl-, and vinylethylbenzene from diethylbenzene on faujasite (89a). 

Rhenium, molybdenum and vanadium ions yield orange, pink and yellow-colored chromatogram zones respectively on a colorless background. 

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