Halides rhenium

Rhenium Halides and Halide Complexes. Rhenium reacts with chlorine at ca 600°C to produce rheniumpentachloride [39368-69-9], Re2Cl2Q, a volatile species that is dimeric via bridging hahde groups. Rhenium reacts with elemental bromine in a similar fashion, but the metal is unreactive toward iodine. The compounds ReCl, ReBr [36753-03-4], and Rel [59301-47-2] can be prepared by careful evaporation of a solution of HReO and HX. Substantiation in a modem laboratory would be desirable. Lower oxidation state hahdes (Re X ) are also prepared from the pentavalent or tetravalent compounds by thermal decomposition or chemical reduction. 

Ligand induced redox reactions of low oxidation state rhenium halides and related systems in non-aqueous solvents. R. A. Walton, Prog. Inorg. Chem., 1976, 21, 105-127 181). 

Solid-state cluster chemistry is dominated by octahedral (M 5L8)L6 and (MsLi2)L units which are the focus of this paper. These two cluster types are different in the way the metal octahedral core is surrounded by the ligands. In (MsLg)L6-type clusters (Fig. 6.1a), typical for molybdenum and rhenium halides, chalcogenides, and chalcohalides, eight innei hgands (L ) cap the octahedron faces and six outer ligands (L ) are located in the apical positions [9]. For metals with a smaller number of valence electrons, the (M6L i2)L -type clusters... 

Rhenium Halides and Related Systems in Nonaqueous Solvents Wang, Hsin, see Pecoraro, Vincent L. Wang, Hua H., see Williams, Jack M. 21 105... 

Rhenium halides, 21 699-700 Rhenium hydrides, 21 700 Rhenium imports, U.S., 21 688t Rhenium oxides, 21 699 Rhenium powder, 21 688, 689, 690, 693 specifications for, 21 694t Rhenium sulfides, 21 699... 

Compounds of the formulas Re(CH3)6, ReO(CH3)4, Li e CH ] [60975-25-9], Re02(CH3)3 [56090-011-8], and Re03CH3 [70197-13-6] have been prepared. The first two compounds were obtained from reaction of rhenium halides or oxyhalides and methyllithium the last three were formed from the species by oxidation or reduction reactions. The use of these hydride and alkyl complexes as catalysts is under investigation. 

In addition to the bimetallic complexes of rhenium and alkaline metals formed as byproducts in the exchange reactions of rhenium halids with alkali alkoxides (such as, for example, LiReO(OPr )5 xLiCl(THF)2 [519]) there has been recently prepared a number ofbimetallic complexes ofrhenium and molybdenum, rhenium and tungsten, and rhenium and niobium [904, 1451]. The latter are formed either due to the formation of a metal-metal bond, arising due to combination of a free electron pair on rhenium (V) and a vacant orbital of molybdenum (VI) atom or via insertion of molybdenum or tungsten atoms into the molecular structure characteristic of rhenium (V and VI) oxoalkox-ides. The formation of the compounds with variable composition becomes possible in the latter case. 

Rhenium Halides and Related Systems in Nonaqueous Solvents. 21 105... 

The synthesis of pentacarbonyl rhenium(I) halides, Re(CO)5X, succeeded from simple and complex rhenium halides below 200 atm of CO at 200° C. The compounds are extraordinarily stable and form easily, often quantitatively, from carbon monoxide and rhenium metal in the presence of other heavy metal halides or halogen sources such as CC14. Later we prepared the corresponding carbonyl halides of manganese (67) and technetium (68) from their respective carbonyls. It was found that the corresponding binuclear tetracarbonyl halides [M(CO)4X]2 (M = Mn, Re) could be made by heating the mononuclear M(CO)5X complexes (15, 69), as well as by other methods. 

Previous preparations of Re3Cl9 have involved driving the rhenium halides horizontally along bulb trains.1 2 The present procedure is a considerable improvement on these, because it involves decomposition of refluxing rhenium pentachloride in the reaction bulb. Yields are very high and, using the method for the preparation of rhenium pentachloride given in Sec. 11, yields of over 90% from rhenium metal are possible. 

The bulb is heated with a medium Bunsen flame until the rhenium pentachloride melts and is refluxing up the tube.t From time to time heating is stopped and Re3Cl9 formed in the tube is scraped back into the bulb. After about 4 hr, or when no more brown fumes are seen and only solid is observed in the bulb, the apparatus is allowed to cool. The bulb is sealed off and transferred to a glove bag and the dark-red crystalline solid is transferred to ampules. The product can be purified by grinding with a mortar and pestle under nitrogen and pumping off any volatile rhenium halide oxides under vacuum. 

Recently, norbornene was reported to undergo ring-opening polymerization in the presence of molybdenum, tungsten, and rhenium halide catalysts (33). In each of these studies (33-35), the catalysis was interpreted by mechanisms involving the scission of the carbon-carbon single bond adjacent to the double bond, e.g., Eq. (12). 

Introduction.—The organometallic chemistry of technetium and rhenium reported during 1974 has been surveyed. The ligand-induced redox reactions of rhenium halides have been reviewed, and the chemistry of cyanide complexes of Group Vila metals has received attention. The electrochemistry of technetium and rhenium has been the subject of two reviews, and a general monograph on the production, uses, and disposal of technetium has appeared. Recently published crystal structures of complexes of technetium and rhenium have been collated. ... 

The Re2(CO)io has also been obtained from reduction of rhenium halides with Na in tetrahydrofuran at 130°C under 250-280 atm CO pressure. However, with alkali metal used for the reduction, the [Re(CO)s] anion or more complicated cluster anions form and hydrolysis is required to sort the carbonyl out of the reaction mixture (70% yield). 

Cyclobutene, cyclopentene, and norbomene also give their polyalken-amers (64). The molecular weights are all high, and the stereochemistries are largely cis. Of these, cw-polypentenamer has also been made with molybdenum, tungsten, and rhenium halide catalysts, and cii-polynor-bomenamer (of lower molecular weight) with a molybdenum chloride catalyst, but polybutenamer made with metal halide catalysts (the metals tried were Ti, Mo, W, V, Cr, and Ru) has never been found to have more than 60% of its double bonds cis (64). 

Walton, R. A., Ligand-Induced Redox Reactions of Low Oxidation State Rhenium Halides and Related System in Nonaqueous dvents. m.m. 21 105... 

The number of cluster species with a triangular array of metal atoms which have been characterized by X-ray diffraction analysis is rather large. Low as well as high-valence triangular clusters are known. The former are numerous and mostly carbonyl species the later are practically restricted to rhenium halides. Selected examples of triangular trinuclear metal clusters are described in Table 2.2. In most cases the metal atoms in the cluster are equidistant, but there are also many examples in which the internuclear distances are not equivalent. 

A are shorter than those observed in the pure metals (2.725 A). Eight chloride ions are coordinating the faces of the octahedron and six are linked terminally to the metal atoms. In these compounds, analogous to rhenium halides, the distances metal-terminal halides are somewhat shorter than those associated to bridging halides. 

The rhenium halide anion [Re3X12] " with 42 electrons is also an electron-poor system. The principal characteristic of a series of tri and tetrarhenium clusters are shown in Table 2.11. The peculiarly short Re-Re distances observed for the halide derivatives agree with the three Re-Re double bonds predicted by the 18-electron rule. 

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