WCl6 Research Articles

Insertion of Ethyl Isocyanate at the Tungsten–Chlorine Bond. Crystal Structure of 1,3,5-Triethyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione

The reaction of tungsten hexachloride with excess ethyl isocyanate in dichloroethane leads to the insertion of three ligand molecules at one of the tungsten–chlorine bonds. The data of elemental analysis and IR spectroscopy confirm that the thermolysis of the reaction mixture affords the WCl4(L3Cl) complex (I), where L = –N(Et)C(O)–. The structure of the chain of inserted molecules in I is established on the basis of IR and NMR data, and the results of X-ray diffraction analysis of crystals of an organic product (II) of the hydrolysis of I. According to the latter, compound (II) is a derivative of s-triazine—1,3,5-triethyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

HIGHLY EFFICIENT AND CHEMOSELECTIVE CONVERSION OF ALDEHYDES TO ACYLALS CATALYZED WITH TUNGSTEN HEXACHLORIDE (WCl6)

ABSTRACT Different types of aldehydes react chemoselectively with acetic anhydride in the presence of a catalytic amount of tungsten hexachloride (WCl6) to produce the corresponding gem-diacetates in good to excellent yields.

Tungsten oxo salicylate complexes from tungsten hexachloride reactions systems.

Tungsten hexachloride is a potent halogen-transfer agent, capable of reacting directly with salicylic acid to generate a tungsten oxo fragment and salicoyl chloride. As a result, oxo complexes dominate the chemistry of tungsten(VI) salicylates. Both mono- and disalicylate substituted tungsten oxo complexes are accessible. The Brønsted free acid W(=O)Cl(Hsal)(sal) complex is a sparingly soluble, presumably polymeric material that can be dissolved in THF. The THF adduct has been characterized by NMR spectroscopy, although an X-ray crystallographic study indicates that the product cocrystallizes with a structurally analogous d(1) WCl(2)(Hsal.THF)(sal) byproduct. The remaining chloride ligand in W(=O)Cl(Hsal)(sal) is replaced by a bridging oxo unit when the reaction contains a significant excess of salicylic acid. The product "linear" oxo bridged ditungsten complex, [W(=O)(Hsal)(sal)](2)O, forms intramolecular hydrogen bonds, accounting for its high solubility in noncoordinating solvents. An X-ray study shows that the intramolecular Hsal.sal hydrogen bonding in this complex accommodates a more linear W-O-W arrangement than does a previously observed class of isostructural diolate derivatives. Tungsten oxo tetrachloride, formed in the initial reaction between salicylic acid and WCl(6), also reacts with the salicoyl chloride byproduct to generate tungsten salicoylate (OAr-2-COCl) complexes.

Preparation and Characterization of Epitaxial Bi2WO6 Thin Films Prepared by a Sol-Gel Process

AbstractWe have succeeded in an epitaxial growth of bismuth tungstate (Bi2WO6, BWO) thin films, one of the bismuth layer-structure ferroelectrics (BLSF), on SrTiO3 (001) single crystal substrates by a spin coating process. BLSF are known to be one of the promising materials for ferroelectric random access memory (FeRAM) devices. A homogeneous coating solution was prepared with tungsten hexachloride and bismuth 2-ethylhexanoate as raw materials, and 2-(2-methoxyethoxy) ethanol and formamide as solvents. The as-coated thin films were sintered at temperatures from 500 to 800°C for lh in air. BWO crystallized at temperatures above 500°C. Any crystal phase was not observed in the thin films except for (001) phases of BWO in the XRD patterns. It was confirmed that the thin film was growing epitaxially by measurement of XRD pole figure. The crystallographic relationship of the film and substrate was BWO(001)//STO(001), BWO[110]//STO[100].

WCl6 chemical transformations occurring during pyrolysis and steam activation of coals + WCl6 mixtures

Different concentrations of WCl6 have been added to three kinds of coking coals before their pyrolysis. The rank of the coal and mainly the volatile matters removed during the heat treatment are of great influence on the transformations of tungsten hexachloride. It first reacts with oxygen present in the starting coal to transform into WO2.9 between ambient and 550°C. From 550°C to 750° the trioxide is reduced to WO2 and a fraction reacts with Ca to form CaWO4 as shown by X-ray diffraction. The total amount of W introduced in the initial mixture is recovered in the resulting green-coke and the total amount of chlorine is removed as HCl. After steam activation, WO2 is oxidised into W24O68.

Die Kristallstruktur von [YbCl2(THF)5]+[WOCl4(THF)]- / Crystal Structure of [YbCl2(THF)5]+[WOCl4(THF)]-

Blue moisture sensitive single crystals of [YbCl2(THF)5]+[WOCl4(THF)]- were obtained as a by-product from the reaction of the ytterbium trisamide Yb[N(SiMe3)2]3 with tungsten hexachloride in THF solution. The crystals were suitable for an X-ray crystal structure determination. Space group P2/c, Z = 2, lattice dimensions at -80 °C: a = 1192.5(1), b = 1117.1(1), c = 1349.9(1) pm, ß = 104.115(7)°, R = 0.0424. The structure consists of cations [YbCl2(THF)5]+ in which the ytterbium atom is coordinated in a pentagonalbipyramidal way by the chlorine atoms in the axial positions and by the oxygen atoms of the THF molecules in equatorial positions. Counterions are the well-known [WOCl4(THF)]- ions.

ChemInform Abstract: Tungsten Hexachloride (WCl6), a Highly Efficient and Chemoselective Catalyst for Acetalization of Carbonyl Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Tungsten Hexachloride (WCl6) in the Presence of Dimethylsulfoxide Promoted Facile and Efficient One‐Pot Ring Expansion—Chlorination Reactions of 1,3‐Dithiolanes and 1,3‐Dithianes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Efficient Deoxygenation of Sulfoxides to Thioethers and Reductive Coupling of Sulfonyl Chlorides to Disulfides with Tungsten Hexachloride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Tungsten Hexachloride (WCl6), A Highly Efficient and Chemoselective Catalyst for Acetalization of Carbonyl Compounds

Various types of aldehydes and ketones could be converted chemoselectively to their corresponding 1,3-dioxanes or diethyl acetals in the presence of catalytic amounts of tungsten hexachloride (WCI6) in good to excellent yields in CH2Cl2 or under neat conditions, respectively.

Synthesis of triblock copolymers (polyA-polybutadiene-polyA) and applications as additives in composite propellants

Hydoxyl-terminated polybutadiene (HTPB), an important polymeric fuel binder for composite propellants, has been utilised to anchor tungsten hexachloride, a well-known metathesis catalyst. This anchored catalyst polymerises various monomers like phenylacetylene (PA) and norbornene (NBE) to give triblock copolymers via metathesis polymerisation. The triblock copolymers thus obtained are of the type polyA- block-polybutadiene- block-polyA and have been characterised by spectroscopic, thermal and gel permeation chromatographic techniques. As block copolymers have the characteristics of the individual polymers, they can be used as substitutes or additives in analogous polymeric formulations to improve the matrix properties. These triblock copolymers obtained from HTPB were employed as additives to a solid propellant mixture based on HTPB with ammonium perchlorate (oxidiser), dioctyl adipate (plasticiser) and toluene diisocyanate (curing agent). Burning rate studies of these propellant mixtures were conducted under various pressures to evaluate the individual ballistic nature. It was found that NBE-based additive imparts higher burning rate than the HTPB-based propellant. The effect of copper chromite as a burning rate modifier in this new formulation was also evaluated. The mechanical properties of the propellants were measured and compared to show the effect of triblock in the binder network. This paper mainly focuses on the synthesis and characterisation of the above triblock copolymers and burning rate studies of the propellants based on these polymers.

ChemInform Abstract: Tungsten Hexachloride (WCl6) as a Mild and Efficient Reagent for Deprotection of Acetals and Ketals.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Tungsten Hexachloride (WCl6) in the Presence of Dimethylsulfoxide Promoted Facile and Efficient One-Pot Ring Expansion-Chlorination Reactions of 1,3-Dithiolanes and 1,3-Dithianes

Tungsten Hexachloride (WCl₆) in the Presence of Dimethylsulfoxide Promoted Facile and Efficient One-Pot Ring Expansion-Chlorination Reactions of 1,3-Dithiolanes and 1,3-Dithianes

Efficient Deoxygenation of Sulfoxides to Thioethers and Reductive Coupling of Sulfonyl Chlorides to Disulfides with Tungsten Hexachloride

Efficient Deoxygenation of Sulfoxides to Thioethers and Reductive Coupling of Sulfonyl Chlorides to Disulfides with Tungsten Hexachloride

SILOXANE-ACTIVATED CATALYTIC SYSTEMS USED IN THE METATHESIS POLYMERIZATION OF NORBORNENE

The activation of the cycloolefin metathesis polymerization by siloxanes is investigated. The system selected for this purpose is the polymerization of norbornene (NBE) in cyclohexane initiated with the tungsten hexachloride (WCl6)/tetramethyltin (SnMe4) system. The siloxane activator is hexamethyldisiloxane (HMDS). The formation and stability of the primary active species are followed through 1H NMR. It is found that such species are generated with the WCl6/SnMe4, WCl6/NBE/HMDS and WCl6/NBE/SnMe4/HMDS systems. The WCl6/NBE system is inactive. Activation of the polymerization system by HMDS is also followed through a kinetic study. The kinetics of norbornene polymerization initiated with WCl6/SnMe4 is used as the reference system and is compared with the WCl6/NBE/HMDS and WCl6/NBE/SnMe4/HMDS polymerization systems. The latter is found to be the most reactive.

ChemInform Abstract: Tungsten Hexachloride (WCl6) as an Efficient Catalyst for Chemoselective Dithioacetalization of Carbonyl Compounds and Transthioacetalization of Acetals.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Facile Reduction of Tungsten Halides with Nonconventional, Mild Reductants. Part 1. Tungsten Tetrachloride: Several Convenient Solid‐State Syntheses, a Solution Synthesis of Highly Reactive (WCl4)x, and the Molecular Structure of Polymeric Tungsten Tetrachloride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Facile Reduction of Tungsten Halides with Nonconventional, Mild Reductants. 2. Four Convenient, High-Yield Solid-State Syntheses of the Hexatungsten Dodecachloride Cluster W(6)Cl(12) and Cluster Acid (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)(), Including New Cation-Assisted Ternary Routes.

Tungsten hexachloride was reduced by Hg or Bi at moderately low temperatures ( approximately 350 degrees C) to afford good yields (Hg, 73%; Bi, 85%) of W(6)Cl(12) after conversion of the reduction product to the chloro acid (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)(), recrystallization, and thermolysis in vacuo. Antimony was a less effective reductant because of the lower yield of chloro acid (31%) and the substantial quantities of insoluble byproducts found after HCl workup. The yield of (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)() from WCl(6) reduction by Sb improved dramatically to 79% with added KCl, while LiCl reduced the yield to only traces. In Bi reduction of WCl(6), the yield of (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)() decreased from 86 to 49% upon addition of NaCl, whereas added KCl had no effect on the yield. The Hg-, Bi-, Sb/KCl-, and Bi/KCl-based routes offer substantial experimental advantages over published methods for preparation of (H(3)O)(2)[W(6)(&mgr;(3)-Cl)(8)Cl(6)](OH(2))(x)() and W(6)Cl(12).

Tungsten Hexachloride (WCl6) as an Efficient Catalyst for Chemoselective Dithioacetalization of Carbonyl Compounds and Transthioacetalization of Acetals

A variety of aldehydes, ketones and O,O-acetals were efficiently converted to the corresponding 1,3-dithianes and 1,3-dithiolanes by using catalytic amounts of tungsten hexachloride (WCl6) in CH2Cl2 under mild conditions.

Tungsten Hexachloride (WCl6) as a Mild and Efficient Reagent for Deprotection of Acetals and Ketals

A variety of acetals and ketals are efficiently and rapidly converted to the corresponding carbonyl compounds by using WCl6 in dichloromethane or acetonitrile at room temperature.