Fluorides silicon halides

Nonmetal Halides. Vigorous or explosive reactions occur with phosphorus tribromide on addition of drops of water,20 phosphorus trichloride, phosphorus pentachloride,21 diselenium dichloride,22 sulfur dichloride, boron tribromide, sulfur dibromide,17 seleninyl bromide,23 phosphoryl chloride, sulfinyl fluoride, silicon tetrachloride, and silicon tetrafluoride.24... 

Higher silicon halides Si X +2 with n > 2 but of limited molecular weight have been known for a long time, above all from chlorine, but a few from bromine, and none from iodine. In the case of fluorine, some higher silicon fluorides derived from difluorosilylene have been recently discovered (see p. 60). 

Due to the high affinity of silicon to oxygen, the silicon halides (except fluorides) are usually easily hydrolyzed by water or alcohols. 

The question of the intermolecular association in silicon halide has a certain interest. Although the infrared spectra of silicon chloride and fluoride adducts have been reported and interpreted in terms of five- and six-coordinate silicon-atoms only the latter adducts have been examined by X-ray diffraction... 

Silicon halides react with complex hydrides to form silanes. Complex hydrides used are LiAlH and to a lesser extent MBH (M = Li, Na, K) . Reductions are carried out in aprotic ether solvents, e.g., Et O, glymes, THE or n-BUjO. These reactions are adaptable to Si—D bond synthesis (see 1.6.7.1.2). Typical syntheses of monosilanes are shown in Table 1. Chlorosilanes are preferred the fluorides react less readily. Bromo- and iodosilanes react easily but offer no advantage over the more available chlorides. ... 

The transformation of cyclopropanes into cyclopropenes by elimination procedures has led to the preparation of several 3- and 3,3-di-substituted l-chloro-2-phenylcyclopropenes. The application of the fluoride-ion-promoted elimination of trisubstituted silicon halide to cyclopropene synthesis provides a simple route to 1-bromo- and 1-chlorocyclopropenes (156 X = Br or Cl) in high yield.Two... 

Halogens, halides. Hydrogen fluoride, hydrogen chloride, chlorine, fluorine, silicon tetrafluoride... 

The palladium-catalyzed cross-coupling of alkenylsilanols has been extensively studied with respect to the structure of both the silicon component and the acceptor halide. The preferred catalyst for coupling of aryl iodides is Pd(dba)2 and for aryl bromides it is [allylPdCl]2. The most effective promoter is tetrabutylammonium fluoride used as a 1.0M solution in THF. In general the coupling reactions occur under mild conditions (room temperature, in 10 min to 12 hr) and some are even exothermic. 

These incorporate membranes fabricated from insoluble crystalline materials. They can be in the form of a single crystal, a compressed disc of micro-crystalline material or an agglomerate of micro-crystals embedded in a silicone rubber or paraffin matrix which is moulded in the form of a thin disc. The materials used are highly insoluble salts such as lanthanum fluoride, barium sulphate, silver halides and metal sulphides. These types of membrane show a selective and Nemstian response to solutions containing either the cation or the anion of the salt used. Factors to be considered in the fabrication of a suitable membrane include solubility, mechanical strength, conductivity and resistance to abrasion or corrosion. 

Hydroelectric turbines, virtual two-way SMA devices in, 22 349-350 Hydroentanglement, 17 507-508 Hydrofinishing, 15 216 Hydroflumethiazide, molecular formula and structure, 5 162t Hydrofluoric acid (HF), 4 579t. See also Hydrogen fluoride North American capacity of, 14 15t production of, 14 15 silicon solubility in, 22 491-492 in sodium fluoride manufacture, 22 825 solubility of boron halides in, 4 140t solubility of metal fluoroborates in, 4 152t... 

Strontium compounds, 23 319-324 estimated distribution of, 23 3201 world production of, 23 319-320 Strontium cyanide, 8 197 Strontium ferrate (1 1), 5 598 Strontium fluoride, 23 323 Strontium fluoroborate tetrahydrate, 4 153 Strontium halides, 23 323 Strontium hexaferrite, 23 323 Strontium hydride, 13 613 Strontium hydroxide, 23 324 Strontium iodide, 23 323 Strontium-lead alloys, 14 779 Strontium minerals, 23 320 producers of, 23 319 Strontium nitrate, 23 319, 321, 323 Strontium oxide, 23 318, 324 Strontium peroxide, 18 396, 23 324 Strontium-silicon alloy, 22 520 Strontium sulfate, 23 322, 324 Strontium sulfide, 23 322 Strontium titanate... 

The yff-cristobalite structure is named after one mineral form of silicon dioxide, S102. The silicon atoms are in the same positions as both the zinc and sulfurs in zinc blende (or the carbons in diamond, which we look at later in Section 1.6.5) each pair of silicon atoms is joined by an oxygen midway between. The only metal halide adopting this structure is beryllium fluoride, Bep2, and it is characterized by 4 2 coordination. 

At present, primarily the binary compounds have been studied, and considerations of product volatility are the most significant driving force behind much of this research. The group III—V compounds are particularly difficult, because the group V elements form volatile halides, whereas group III halides, particularly the fluorides, tend to be involatile. As a result, F source plasmas, which have been the mainstay of silicon technology, are... 

Other theoretical studies discussed above include investigations of the potential energy profiles of 18 gas-phase identity S 2 reactions of methyl substrates using G2 quantum-chemical calculations," the transition structures, and secondary a-deuterium and solvent KIEs for the S 2 reaction between microsolvated fluoride ion and methyl halides,66 the S 2 reaction between ethylene oxide and guanine,37 the complexes formed between BF3 and MeOH, HOAc, dimethyl ether, diethyl ether, and ethylene oxide,38 the testing of a new nucleophilicity scale,98 the potential energy surfaces for the Sn2 reactions at carbon, silicon, and phosphorus,74 and a natural bond orbital-based CI/MP through-space/bond interaction analysis of the S 2 reaction between allyl bromide and ammonia.17... 

Due to the presence of silicon which stabilizes the a-carbanion, strong bases such as butyllithium and sodium amide are able to give an ylid from silylmethylammonium halides. Fluoride ion-assisted desilylation of these salts represents another means to create an ylid. These ylids are prone to rearrange and the results differ upon the nature of... 

Binary Compounds and Related Systems.- Halides. New simple reductive fluoride elimination routes to MoF4 and MoF5 have been reported. MoF6 is conveniently reduced by elemental silicon (4 1) or by dihydrogen (2 1) in anhydrous HF to produce MoF5. This compound in turn may be reduced by elemental silicon (4 1)... 

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