Rhenium trichloride

Submitted by Loren C. Hurd and Eugene Brimm Checked by W. A. TAEBELf and B. S. Hopkins f 

Rhenium trichloride is prepared by the thermal decomposition of rhenium pentachloride in an atmosphere of nitrogen.1 

A combustion tube of either Jena hard glass or Corning 172 is constructed similar in design to that used for the preparation of rhenium pentachloride (synthesis 62). The pentachloride is prepared in the manner previously described and sublimed into the bulb D. The chlorine is then turned off, and the train swept out with nitrogen. When all chlorine has been displaced, the pentachloride is 

If a pure product is desired, the tube is sealed off at the first constriction after all of the pentachloride has been decomposed. The product is shaken into bulb D, the tube inclined at an angle of 45°, and the chloride sublimed under reduced pressure at a temperature of 450°C. An asbestos shield placed at the point where the tube enters the furnace will assure condensation of trichloride just beyond the edge of the furnace. The product is sublimed twice, allowed to cool to room temperature, and the tube broken just above and below the point where the trichloride has formed. The dark-red crystalline mass may be powdered, transferred to a weighing bottle, and stored in a desiccator without fear of decomposition. Exposure to direct sunlight should be avoided because of the formation of oxychlorides under such conditions. The yield is usually about 60 to 65 per cent based upon the quantity of rhenium used. In one experiment, 38 g. of twice resublimed rhenium trichloride was prepared with a yield of 68 per cent. 

Geilmann, Wrigge, and W. Biltz Nachr. Ges. Wiss. Gottingen Geschaft. Mitt. Math, physik., Kl. V, 29, 579 (1932) Chem. Abslr., 28, 60 (1934). 

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Rhenium pentachloride, 180 Rhenium sulfide, 177 Rhenium trichloride, 182 Rubidium, metallic, 79... 

Shortly after rhenium was discovered, rhenivim trichloride was prepared by thermal decomposition of rhenium pentachloride (172, 205). Reaction of rhenium trichloride with cesium chloride in hydrochloric acid produced a dark red salt of stoichiometry CsReCli ... 

Other elements often separated from pile or cyclotron targets by distillation or volatilisation are tritium (3), germanium as the bromide (23), arsenic as the trichloride (67), technetium (23), (91), rhenium (24), (25) and osmium (25) as oxides. 

Rhenium reacts with all halogens including iodine to yield hahdes in several valence states from -i-1 to -i-6. Such hahdes include dark red hexagonal trichloride, Reds, dark green pentachloride, ReCls, green hexafluoride, ReFe, and the greenish black crystalline tribromide, ReBrs. 

The complexes [M(CO)5(> 2-C2H4)] [A1C14] (M = Mn, Re) were first prepared by abstraction of the chloride ligand in M(CO)sCl using aluminum-trichloride under ethylene pressure.14 The preparation of [BF4] salts of these cationic pentacarbonylethene complexes of manganese and rhenium proceeds under very mild conditions (1 bar) and gives high yields.6... 

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. 

The reactions of iron carbonyls with diorgano tellurides deserve mention, for example the reaction of Fe3(CO),2 with PhjTe gives Ph2TeFe(CO>4, whilst several ruthenium-carbonyl complexes have been prepared from reactions between diphenyl telluride and alcoholic carbon monoxide-saturated solutions of ruthenium trichloride hydrate. Various other ruthenium-carbonyl complexes of diorgano teUurides, including di- and tri-substituted species, have also been described. The utility of diphenyl telluride in transition metal carbonyl chemistry has also been well illustrated during studies of manganese and rhenium compounds. 

Haloform reactions are generally performed with halogens in the presence of hydroxide [251] or directly with hypohalites [252]. Alternative methods affording carboxylic acids from methyl ketones (or other enolizable substrates) include the aerobic oxidation in the presence of a catalytic amount of dinitrobenzene [253] with a base in a dipolar aprotic solvent such as DMF [254] or HMPT (hexamethylphospho-ric triamide) [255, 256] and the use of stoichiometric quantities of hypervalent iodide derivatives [95, 257] or nitrosylpentacyanoferrate [258]. Furthermore, metal catalysts can be used, and systems such as tert-butyl hydroperoxide in the presence of rhenium oxide [259], oxygen in combination with a copper complex [260], heteropolyacids [261] and Mn"/Co" systems [262] were found to be applicable. Finally, aryl ketones are selectively oxidized to aliphatic carboxylic acids by treatment with periodate [81] in the presence of ruthenium trichloride [263]. 

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