Silicon-oxygen compounds

Schematic representation of cristobalite, one of the crystalline forms of silica, which is based on tetrahedral Si04 groups joined at the apices. Quartz, the more common form of Si02, has a similar, but more condensed, structure. 

An electron micrograph image of the hairs on the leaf of a stinging nettle. 

The silicate structures are conveniently described in terms of the [Si04] unit, in which there is tetrahedral coordination of silicon by oxygen (Structure 10.4). 

In minerals, these occur as discrete tetrahedra or are linked by one or more comers to give one-dimensional (chains), two-dimensional (sheets) or three-dimensional structures. Examples of all these types are illustrated in Silicate structures on one of the CD-ROMs associated with this book note particularly how the sharing of oxygen atoms between tetrahedra determines the dimensionality of the silicate stmcture. 

Double chains Ampliiboles (note the hexagonal ring structures. These include the fibrous asbestos minerals. 

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Silicon-Oxygen Compounds From Molecules to Materials, Vieweg, Wiesbaden, 1996 p. 171. 

Although apparently no Si NMR data have yet been published for MesSiOH 4, several silicon-oxygen compounds, for example TMSOTf 20 [11], hexamethyldisil-... 

Tacke, R. Dannappel, O. In Tailor-made Silicon-Oxygen Compounds—From Molecules to Materials Corriu, R. Jutzi, P., Eds. Vieweg Braunschweig/Wiesbaden, 1996 pp. 75-86. 

It was recognized at an early stage in the development of silicon-transition-metal chemistry that silicon-oxygen compounds often appeared, either as by-products from preparations or as decomposition products on heating or even on storage. At first, adventitious hydrolysis or oxidation was blamed, but it soon became clear that attack on silicon by oxygen of coordinated carbonyl groups was responsible. Since metal carbonyls are known to form adducts with Lewis acids such as compound (XXXIII) (286),... 

The chemistry of silicon oxygen compounds with SiOs and SiC>6 skeletons in aqueous solution is of special interest. It has been speculated that such Si(IV) complexes with ligands derived from organic hydroxy compounds (such as pyrocatechol derivatives, hydroxycarboxylic acids, and carbohydrates) may play a significant role in silicon biochemistry by controlling the transport of silicon. 

M. G. Walawalker, R. Murugavel and H. W. Roesky, in Tailor-Made Silicon Oxygen Compounds (Eds. R. Corriu and P. Jutzi), Vieweg, Braunschweig Weisbaden, 1996, p. 61. 

The fundamental silicon-oxygen compound is silica, which has the empirical formula Si02. Knowing the properties of the apparently similar compound carbon dioxide, one might expect silica to be a gas that contains discrete Si02 molecules. In fact, nothing could be further from the truth—... 

Silica the fundamental silicon-oxygen compound, which has the empirical formula Si02, and forms the basis of quartz and certain types of sand. (16.5)... 

Table 1. Hydride Reduction of Silicon-Oxygen Compounds...

R4 Si(OR ) + n R"A1H R AIOR + R4 SiH (b) Typical reactions and products are listed in Table 1. Reductions involving in NaCl-AlClj solvents or Hj in the presence of Na involve AlClj Hj or NaH, respectively, as reductant species. Table 1. Hydride Reduction of Silicon-Oxygen Compounds ... 

E. Hengge, A. Kleewein, in Tailormade Silicon-Oxygen Compounds - from Molecules to Materials (Eds. P. Jutzi, R. J. P. Corriu), Vieweg Verlag, Braunschweig, 1996, pp. 89-98. 

Therefore, the two single bonds will always be better enthalpically than one double bond. If silicon atoms only have single bonds to oxygen atoms in silicon-oxygen compounds, the structure around each silicon atom will be tetrahedral each silicon will have four single bonds to four different oxygen atoms. 

El4.21 Glasses are amorphous silicon-oxygen compounds. Starting from sand (which is mostly pure SiOi) and other oxide additives, a wide variety of glasses with different properties can be obtained, used and seen every day. Activated carbon (used as adsorbent), carbon fibres (used as additives in plastic to increase the strength), and carbon black (used as pigment) are three examples of amorphous and partially crystalline carbon. 

Leonhard Birkofer and Oskar Stuhl XI. SILICON-OXYGEN COMPOUNDS... 

Cyclic silicon-oxygen compounds (e.g. silaoxa-heterocycles)... 

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