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Refractory metals have high melting points, with tungsten and rhenium the highest of all elements, and the other's melting points only exceeded by osmium and iridium, and the sublimation of carbon. These high melting points define most of their applications. All the metals are body-centered cubic except rhenium which is hexagonal close-packed.
Rhenium compounds are known for all the oxidation states between −3 and +7 except −2. The oxidation states +7, +4, and +3 are the most common. [32] Rhenium is most available commercially as salts of perrhenate, including sodium and ammonium perrhenates. These are white, water-soluble compounds. [33] Tetrathioperrhenate anion [ReS 4] − is ...
Rhenium(VI) oxide has an appearance similar to that of copper. Rhenium(IV) oxide (or rhenium dioxide) is an oxide of rhenium, with the formula ReO 2. This gray to black crystalline solid is a laboratory reagent that can be used as a catalyst. It adopts the rutile structure. It forms via comproportionation: [4] 2 Re 2 O 7 + 3 Re → 7 ReO 2
It is the raw material for all rhenium compounds, being the volatile fraction obtained upon roasting the host ore. [26] Rhenium, in addition to the +4 and +7 oxidation states, also forms a trioxide. It can be formed by reducing rhenium(VII) oxide with carbon monoxide at 200 C or elemental rhenium at 4000 C. [27] It can also be reduced with ...
Oxotrichlorobis(triphenylphosphine)rhenium(V) is the chemical compound with the formula Re O Cl 3 (P Ph 3) 2. This yellow, air-stable solid is a precursor to a variety of other rhenium complexes. [1] In this diamagnetic compound, Re has an octahedral coordination environment with one oxo, three chloro and two mutually trans triphenylphosphine ...
Land Rover's Type 9013 20-inch aluminum wheel is now in production as part of the $5950 County exterior pack, which also includes snazzy two-tone white-and-Tasman-Blue paint and is not to be ...
The vehicles have wheels with rubber tires that run on a roll way inside guide bars for traction. Traditional, flanged steel wheels running on rail tracks provide guidance through switches and act as backup if tyres fail. Most rubber-tyred trains are purpose-built and designed for the system on which they operate.
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