Chlorine rhenium chlorides

Promoters, usually present in smaU amount, which enhance activity or retard degradation for instance, rhenium slows coking of platinum reforming, and KCl retards vaporization of CuCU in oxy-chlorination for vinyl chloride. 

Treatment of the rhenium sulfide chlorides with an excess of chlorine at temperatures above 450°C results in formation of ReCls 140). Reduction between 350 and 500°C gives binary rhenium chalcogenides 139,262). Action of water vapor on rhenium sulfide chlorides at 350-500°C produces oxysulfides 139). 

Rhenium pentachloride reacts energetically with water. If exposed to air, it fumes and evolves chlorine and hydrogen chloride. 

The platinum-catalyzed reaction of alkanes with chlorine leads to alkyl chlorides and alcohols (Table 6, entry 46) with modest rates and conversions [50], Cydooctane can be easily dehydrogenated (Table 6, entry 47) in the presence of a stabilized vinylalkane by use of the neutral rhenium compound ReH7(PR3)2 [51]. By employing an iridium-based catalyst, the photochemical dehydrogenation of methylcydohexane to methylenecyclohexane is performed at room temperature... 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

Rhenium Pentachloride and Volatile Metal Chlorides by Direct Chlorination 41... 

RHENIUM PENTACHLORIDE AND VOLATILE METAL CHLORIDES BY DIRECT CHLORINATION USING A VERTICAL-TUBE REACTOR... 

The chlorination of rhenium to rhenium pentachloride1 and of other metals to volatile chlorides is conventionally done by passing chlorine over metal... 

Rhenium pentachloride is obtained as black crystals. The solid melts at 261° with decomposition. It fumes in air, evolving hydrogen chloride and chlorine. 

Rhenium oxide tetrafluoride and rhenium oxide pentafluoride can be used as selective fluorination agents reacting with CH2C12 by chlorine-fluorine exchange with > 90% selectivity and, in the case of ReOF5, subsequent decomposition of the unstable Revu chloride species results in ReOCl4 [348]. 

Bis(triarylphosphoranylidene)sulfamides and iV ,iV-dialkyl-iV -(triarylphosphoranylidene)-sulfamides, synthesis 30 Chlorine (I) nitrate, synthesis 33 Anhydrous metal chlorides, synthesis 35 Complexes of rhenium(V), synthesis 38... 

For the analysis of rhenium, the sample is fused with sodium peroxide and rhenium precipitated from hydrochloric acid solution as Re2S7 by hydrogen sulfide. The precipitate is dissolved in aqueous sodium peroxide and from dilute sulfuric acid solution, rhenium is determined by electrodeposition.8 Chlorine is determined gravimetrically by fusion of the sample with a sodium carbonate/ sodium nitrate mixture (95 5) in a platinum crucible and then precipitating as silver chloride. 

Heating ReCl5 in a nitrogen atmosphere causes it to lose chlorine, forming rhenium(m) chloride (see below). 

Cathodic voltammograms, obtained for the purpose of studying the electrochemical behaviour of rhenium in the NaCl melt (the necessary rhenium concentration was secured by the direct chlorination of rhenium metal in sodium chloride), display a well-reproducible distinct peak (Fig.l). The differential volammetric curve also contains only one wave (Fig.2). The cyclic... 

As will be discussed in more detail in Chapter 15, there are three distinct bonding mechanisms which contribute to the metal-metal bonding in [C Re-ReC ] ", tr, n and 3 (the chlorines are all terminal and eclipsed), and so it is an anion of particular interest. It is readily prepared from the commercially available ReClj, which consists of molecules containing a triangle of rhenium atoms, by fusion in molten (220 °C) diethylammonium chloride ... 

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