Bonds silicon halides

Silicon halides are typically tetrahedral compounds. The siUcone—halogen bond is very polar thus the siUcon is susceptible to nucleophilic attack, which in part accounts for the broad range of reactivity with various chemicals. Furthermore, reactivity generally increases with the atomic weight of the halogen atom. 

Because carbon bonds so readily with itself, there are many hydrocarbons (see Chapter 18). Silicon forms a much smaller number of compounds with hydrogen, called the silanes. The simplest silane is silane itself, SiH4, the analog of methane. Silane is formed by the action of lithium aluminum hydride on silicon halides in ether ... 

It has been noted (Section II,B,1) that reactions between transition metal carbonyl anions and silicon halides often fail to produce species containing silicon-transition metal bonds, and that such failure has been ascribed to nucleophilic attack by carbonyl oxygen. It is therefore interesting that compounds containing Si—O—C—transition metal linkages have recently been isolated from such reactions [Eqs. (105) (R = Me, Ph) 183) and (106)... 

Another method of sand control is use of a silicon halide which reacts with water at the surface of sand grains forms SiO which can bond the grains together (55). Reducing the cost of sand consolidation could be very useful since the applicability of gravel packing methods is limited by the bottom hole circulating temperature and the limited temperature stability of polysaccharide polymers. 

Some applications of the use of substituted disilyl mercury compounds, Hg(SiXa)2 (X = Me,Cl), are shown in Table III there is an early review article (421). In most cases, the mercury compound reacts with a metal-halogen bond to give a silicon halide and mercury as byproduct, e.g. (entry 1),... 

Formation of inorganic silicohalides via silicohalide-mercury compounds is also possible (see Chapter 3 Silicon Halides with Si-Si Bonds) ... 

The intermediate metal hydride has been isolated on occasion for Co and Mn , and Eq. (b) has actually been used to prepare silicon-metal bonds (see 5.2.3.2.2.). Inspection of Table 1 reveals the ease of reaction of Co2(CO)g compared with the other carbonyls. Normally this reaction is performed simply by condensing volatile silane onto the carbonyl in the absence of solvent and then allowing rapid reaction in the liquid phase at room temperature, but for the remaining carbonyls it is necessary to use elevated temperatures and sealed, evacuated tubes. The products are volatile and readily purified by vacuum fractionation or sublimation, but are often oxygen and moisture sensitive. The route is most efficient for RjSi derivatives of Co, Mn and Re, which are not generally obtainable by the reactions of silicon halides with metal carbonyl anions (see S.8.3.3.I.). In this way lCo(SiR,)(CO -] = Et, Phj, Clj -, (OEt)j, F/, ... 

Formation of Silicon-Transition and Inner Transition-Metal Bond 239 5 8.3.3. from Silicon Halides... 

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. ... 

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