Tungsten double chlorides

Cationic polymerization of substituted alkyl-1,3-butadienes is accompanied by a considerable loss of double bonds (up to 80%) due to the formation of cyclic products [346]. Tin(IV) chloride in trichloracetic acid, tungsten(VI) chloride, and boron trifluoride etherate have been tested as cationic catalysts [347, 348]. In addition to polymerization, isomerizations are observed with these catalysts. 

In the case of molten salts, the functional electrolytes are generally oxides or halides. As examples of the use of oxides, mention may be made of the electrowinning processes for aluminum, tantalum, molybdenum, tungsten, and some of the rare earth metals. The appropriate oxides, dissolved in halide melts, act as the sources of the respective metals intended to be deposited cathodically. Halides are used as functional electrolytes for almost all other metals. In principle, all halides can be used, but in practice only fluorides and chlorides are used. Bromides and iodides are thermally unstable and are relatively expensive. Fluorides are ideally suited because of their stability and low volatility, their drawbacks pertain to the difficulty in obtaining them in forms free from oxygenated ions, and to their poor solubility in water. It is a truism that aqueous solubility makes the post-electrolysis separation of the electrodeposit from the electrolyte easy because the electrolyte can be leached away. The drawback associated with fluorides due to their poor solubility can, to a large extent, be overcome by using double fluorides instead of simple fluorides. Chlorides are widely used in electrodeposition because they are readily available in a pure form and... 

Tungsten Hexafluoride, WFg, is obtained by the action of anhydrous hydrogen fluoride upon tungsten hexaehloride in platinum vessels, or by the interaction of antimony peiitafluoride with the hexa-chloride. It is a solid at low temjreratures just above 0° C. it sublimes to a heavy gas which fumes in moist air it reacts with water with production of tungstic acid. It attacks both glass and mercury by alkalies it is decomposed, and with alkali fluorides it forms double salts. 

A double hyd roxychloride of tungsten with potassium chloride has been prepared by the reduction with tin of a solution of potassium tungstate in concentrated hydrochloric acid after a series of colour changes the compound K2W(OH)CIg, which is stable in the dry condition, is obtained. 

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). 

Beryllium Sulphide.—Wohler (1828 2) supposed he had made a sulphide by heating the metal with sulphur, but Fremy (1853 1) states that it was the only sulphide he could not produce by I>assing the vapor of carbon disulphide over the hot oxide. De-bray (1855 i) and Nilson and Pettersson (1873 3) state that beryllium and sulphur do not combine when heated together. Berzelius (1826 2) supposed he produced a double sulphide of bci yllium and tungsten, but his results lack confirmation. Lebeau (1899 ii) at last made the sulphide by heating the anhydrous chloride and iodide with. sulphur or with hydrc en sulphide. Also by the action of sulphim vapor on the carbide at a high temperature, lire. sulphide is a white solid, immediately decomposed by water. No other details are given nor further study of this compound been made. 

Carbene complexes have also been shown to undergo a-hydrogen elimination, in this case to form alkylidyne complexes. This reaction is much less common than the reaction of alkyl complexes to form alkylidenes, but a few examples are well documented. Two examples of this transformation are shown in Equations 10.39 and 10.40. Schrock reported the first direct observation of this transformation (Equation 10.39). ° In this first example, an isolated carbene complex converted to an alkylidyne hydride complex upon abstraction of a chloride ligand with trimethylaluminum. In a second example, a double C-H activation process by two sequential a-hydrogen elimination reactions converts the starting tungsten-methyl complex in Equation 10.40 into a methylidyne complex. ... 

Bersch (1901) describes Tessie du Motay s blue as prepared from 10 parts sodium tungstate, 8 parts tin crystals , 5 parts yellow prussiate and 1 part of iron(lll) chloride these are dissolved separately and mixed. The precipitate is washed and exposed to light in thin layers, with the blue colour developing over a period of a few days. According to the discoverer, the pigment consists of a compound of tungsten oxide with a double cyanide of iron and tin . 

Olefin metathesis as a method for the construction of double-bonds has been severely limited by the narrow range of substituents which can be tolerated. Daly and McKervey have discovered that the use of a mixture of tungsten hexachloride and trimethyltin chloride allows the use of tosylate as a substituent, and the general use of [2 -1- 2] cyclo-reversions has been reviewed. 

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