Silicon tetrachloride, structure

Silicon tetrachloride is a colourless liquid, b.p. 216.2 K, and again the molecule has a covalent structure. Silicon tetrachloride is hydrolysed by water ... 

These three frameworks and the framework for glycine in Figure 9 illustrate an important point about Lewis structures. Although Lewis structures show how atoms are connected to one another, a Lewis structure is not intended to show the actual shape of a molecule. Silicon tetrachloride is not flat and square, SO2 is not linear, and the fluorine atoms in CIF3 are not all equivalent. We describe how to use Lewis structures to determine the shapes of molecules later in this chapter. 

Methyltrichlorosilane is produced by the Grignard reaction of silicon tetrachloride and methylmagnesium chloride (structure 17.24). Dimethyldichlorosilane, used in the synthesis of polydimethylsiloxane, is obtained by the reaction of methylmagnesium chloride and methyltrichlorosilane (structure 17.25). 

The zeolite dealumination mechanism is illustrated in Scheme 2.1.6.2. During treatment with silicon tetrachloride, a dealumination method first reported by Beyer et al. [50], the faujasite s framework aluminum was isomorphously replaced by silicon while maintaining the microporous structure. The reaction was self-... 

For about 75 years the silicon tetrachloride molecule (which we select as an example) was assigned the simple valence-bond structure A. G. N. Lewis introduced the practice of showing the unshared... 

Silicon tetrachloride is made by chlorination of Si at red heat. Hexachlorodisilane (Si2Cl6) can be obtained by interaction of SiCL, and Si at high temperatures or, along with SiCL, and higher chlorides, by chlorination of a silidde such as that of calcium. The higher members, which have highly branched structures, can also be obtained by amine-catalyzed reactions such as... 

Denmark et al. have extended this study to the enantioselective ring opening of meso-epoxides with silicon tetrachloride catalyzed by chiral phosphoramide 71 (Table 11). In this case, enantiomerically enriched chlorohydrins have been synthesized in enantiomeric excesses varying from 7 to 87 depending on the structure of the considered substrate [68]. 

Some ceramic materials are not found widely or at all in nature, and thus are synthesized for use. To prepare more complex ceramic compositions such as perovskites of general structural formula ABO3, and ferrites, of formula MFc204, the individual oxides or salts of the cations A, B, and M are often combined as powders and then reacted at high temperature by a solid-state diffusion mechanism. Silicon nitride (Si3N4) can be manufactured from either the nitridation of silicon metal or from the reaction of silicon tetrachloride with ammonia. Silicon carbide (SiC) is obtained from the reduction of silica with a carbon containing source. 

Taking into account that non porous aerosil particles have a spherical structure, this theoretical treatment is applicable also in this case. A silica represents a heterochain inorganic polymer of silicic acid. However, most of its modifications are difficult to characterize in such terms as molecular mass and amount of functional groups per monomer unit and this question is still under discussion. However, such estimates can be made for aerosil, a highly disperse silica produced by combustion of silicon tetrachloride in the oxygen hydrogen flame. 

Because carbon and silicon are both elements in group 14 on the periodic table, we expect them to react with other elements in similar ways. To some extent, they do, but in some cases, carbon and silicon compounds that seem to have analogous structures have very different chemical characteristics. For example, carbon tetrachloride, CCI4, is very stable in the presence of water, but silicon tetrachloride, SiCl4, reacts quickly with water. The unbalanced equation for this reaction is... 

Silicon accounts for 27.7% of the mass of the Earth s crust and occurs in a wide variety of silicates with other metals, clays, micas, and sand, which is largely Si02. The element is obtained on a small scale by the reduction of silicon(IV) oxide (Si02) by carbon or calcium carbide. For semiconductor applications very pure silicon is produced by direct reaction of silicon with an HCI/CI2 mixture to give silicon tetrachloride (SiCb), which can be purified by distillation. This is then decomposed on a hot wire in an atmosphere of hydrogen. For ultra-pure samples zone refining is used. Unlike carbon, silicon does not form allotropes but has only the diamond type of structure. 

Certain very finely divided colloidal silica powders such as those made by the fume process by burning a mixture of silicon tetrachloride and methane, have a sufficiently discrete, particulate structure that such powders can be dispersed in water by colloid milling to give a sol useful in this invention. It is also obvious that such a powder can also be colloid milled directly into a solution of silicate. 

Summary The treatment of silicon tetrachloride with two equivalents of 2-dimethyl-aminomethylferrocenyllithium (1), (FcN)Li, affords (FcN)2SiCl2 (2). The structure of 2 has been determined by X-ray diffraction analysis. It was used as starting chlorosilyl compound for reaction with Na[(ri -C5Me4Et)Mo(CO)3]. The reaction of 1 with 1,6-dichloro-dodecamethylhexasilane yields the novel (FcN)(SiMe2)6(FcN) (4). 

The reinvestigation of reactions of [2-(dimethylaniinomethyl)ferrocenyl]lithium (1), (FcN)Li, with silicon tetrachloride has delivered new analytical data for (FcN)SiCl3, especially X-ray structure analysis results showing pentacoordination of the silicon atom [4]. The treatment of silicon tetrachloride with two equivalents of (FcN)lithium (I) results in (FcN>2SiCl2 (2) as a reddish solid (Scheme 1). 

Silicon nitride (Si3N4) is a major industrial material which is produced extensively by CVD for electronic and structural applications. It is an excellent electrical insulator and diffusion barrier (to sodium and water vapor) and has replaced CVD oxides in many semiconductor devices.l l Silicon nitride coatings are produced by the reaction of silicon tetrachloride (SiCl4) with ammonia ... 

For example, termination of a living anionic polymerization with a tetrafunctional electrophile such as silicon tetrachloride will produce a four-armed star polymer as shown in equation 7. Given that PLi is a well-defined living polymer, a branched polymer with a predictable, well-defined structure will be formed from the linking reaction. 

The crystal structure of silicon is similar to that of diamond however, the Si—Si bonds (226 kJ/mol) are weaker than the C—C bonds (356 kJ/mol), and silicon is not nearly as hard. There is no graphitic allotrope of silicon. Crystalline silicon is a blue-gray, somewhat shiny, brittle element that certainly appears metallic however, it is classified as a nonmetal or metalloid because it is a semiconductor that is, at low temperatures it is an insulator. However, when heated sufficiently, its electrical conductivity increases markedly. Very pure silicon for transistors is produced by reducing silicon tetrachloride prepared by... 

Denmark SE, Eklov BM (2008) Neutral and cationic phophoramide adducts of silicon tetrachloride synthesis and characterization of their solution and solid-state structures. ChemEur J 14 234-239... 

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