Organosilicon compounds hydrides

The first examples of optically active organosilicon compounds, methyl-1-naphthyl-phenylsilicon chloride, hydride and methoxide... 

Stannum, Plumbum). It is not the central metallic atom that is named, but only its hydride MH4 (germane, stannane, plumbane) and the substituents which replace hydrogen atoms in the hydride molecule. Compounds in which the metal atom valence is either higher or lower than 4 are named in analogy to the nomenclature of organosilicon compounds. 

HetflejZ, J., F. Mares, and V. Chvalovskp Organosilicon Compounds. XXXIX. Effect of (p—h1)7t dative bonds on solvolysis of organosilicon hydrides. Collect, czechoslov. chem. Commun. 30, 1643—1653 (1965). 

Besides HFC reaction of preliminarily prepared cyclic organosiloxanes with functional groups and difunctional organosilicon compounds, which give an opportunity to preserve cyclic groups in the polymeric backbone, hydride polyaddition is also widely used, which proceeds under soft conditions and does not involve cyclic structures, introduced into the backbone. 

Section 3 is devoted to the complexes of hydride, alkyl, alkenyl, and silyl ligands. Hydrido see Hydride Complexes of the Transition Metals) and alkyl complexes of most transition metals, and in particular those of nickel, are often involved in many catalytic processes of conunercial importance therefore, an in-depth understanding of the fundamental reactivities of these complexes is crucial to expanding their practical apphcations. Silyl complexes are involved in the transformations of organosilicon compounds, and for this reason their basic reactivities and structural properties are of interest. 

Therefore, the aim of this work was to synthesize new silacyclic and oligomeric organosilicon compounds containing easily modifiable Sl-O-R bonds, via competitive silylative coupling cyclization and polycondensation of divlnyl-substltuted silyl ethers in the presence of ruthenium hydride complex. 

Silicon compounds with coordination number larger than four are the object of many studies first with respect to their application as catalysts in organic and inorganic syntheses and second as starting materials for the preparation of a broad variety of organosilicon compounds [1]. Additionally, hypervalent silicon hydride compounds can successfully be used as model compounds to study, for instance, the mechanism of nucleophilic substitution reactions, which is of great interest since the silicon atom is able to easily extend its coordination number [1]. Moreover, hypervalent silanes are suitable as starting materials for the synthesis and stabilization of low-valent silanediyl transition metal complexes [2-5]. 

Hydrosilylation of unsaturated organosilicon compounds has also found several applications in molecular and polymer organosilicon chemistry. In particular, the addition of polyfunctional silicon hydrides to poly(vinyl)organosiloxane, catalyzed exclusively by Pt compounds and providing an activated cure for silicon rubber [10], has been of great practical importance. Hydrosilylation of the vinyl group at silicon seems to be effective synthetic method for preparation of oligomers and polymers with a linear or cyclolinear stmcture (polyhydrosilylation), and can occur either via the addition of dihydro-carbosilanes and -siloxanes to divinyl-silanes and -siloxanes [25, 26] or by intermolecular hydrosilylation [4] (eq. (1)). 

Several types of organosilicon compounds can be used in cross coupling, fluoride usually being required to activate the silicon for the transmetallation in the earlier examples. Silanols are newer and more versatile reagents, in particular dimethylsilanols, which are used with bases - either reversible (aUcoxides and cesium carbonate) or irreversible (sodium hydride aud sodium hexamethyldisilazide). lu the latter case, the silauo-ate salts can be isolated and stored. ... 

Although this chapter concentrates on organosilicon compounds, a few purely inorganic compounds are also included (the hydrides and halides), since these provide inevitable reference points. It is worth mentioning at this point that the chapter title Thermochemistry is used with its traditional meaning here to signify heats (or enthalpies) of reaction, rather than in the looser sense of chemistry under the action of heat as employed by some workers in the field of organosilicon chemistry. Unless otherwise stated, all standard heats of reaction and heats of formation refer to the gas phase at 298.2 K. 

Uneyama K (1987) Electrogenerated acid-catalyzed reactions of acetals, aldehydes, and ketones with organosilicon compounds, leading to aldol reactions, allylations, cyanations, and hydride additions. Bull Chem Soc Jpn 60 2173-2188. doi 10.1246/... 

The first stage of the above synthesis is an example of a well-known route to organosilicon compounds, including fluoroalkyl derivatives. Such u.v.-initiated additions of silicon hydrides across olefinic bonds have been presumed to occur by a free-radical mechanism similar to that proposed for... 

It is well known that strong electrophiles such as carbocations are reduced by organosilicon hydrides (Eq. 1).3,70,71 On the other hand, simple mixtures of organosilicon hydrides and compounds with weakly electrophilic carbon centers such as ketones and aldehydes are normally unreactive unless the electrophilicity of the carbon center is enhanced by complexation of the carbonyl oxygen with Brpnsted acids3,70 73 or certain Lewis acids (Eq. 2).1,70,71,74,75 Using these acids, hydride transfer from the silicon center to carbon may then occur to give either alcohol-related or hydrocarbon products. 

Alternatively, unreactive mixtures of organosilicon hydrides and carbonyl compounds react by hydride transfer from the silicon center to the carbon center when certain nucleophilic species with a high affinity for silicon are added to the mixture.76 94 This outcome likely results from the formation of valence-expanded, pentacoordinate hydrosilanide anion reaction intermediates that have stronger hydride-donating capabilities than their tetravalent precursors (Eq. 6).22,95 101... 

Alkenes to Alkanes. The ionic hydrogenation of many compounds containing carbon-carbon double bonds is effected with the aid of strong acids and organosilicon hydrides following the n-route outlined in Eq. 2. A number of factors are important to the successful application of this method. These include the degree and type of substituents located around the double bond as well as the nature and concentrations of the acid and the organosilicon hydride and the reaction conditions that are employed. 

The use of deuterated organosilicon hydrides in conjunction with proton acids permits the synthesis of site-specific deuterium-labeled compounds.59 126 221 Under such conditions, the deuterium atom in the final product is located at the charge center of the ultimate carbocation intermediate (Eq. 62). With the proper choice of a deuterated acid and organosilicon hydride, it may be possible to use ionic hydrogenation in a versatile manner to give products with a single deuterium at either carbon of the original double bond, or with deuterium atoms at both carbon centers.127... 

Trisubstituted Alkenes. With very few exceptions, trisubstituted alkenes that are exposed to Brpnsted acids and organosilicon hydrides rapidly undergo ionic hydrogenations to give reduced products in high yields. This is best illustrated by the broad variety of reaction conditions under which the benchmark compound 1-methylcyclohexene is reduced to methylcyclohexane.134 146,192 202 203 207-210 214 234 When 1-methylcyclohexene is reduced with one equivalent of deuterated triethylsilane and two equivalents of trifluoroacetic acid at 50°, methylcyclohexane-... 

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