Silanols silanediols

For a very recent review article on the chemistry of silanols, silanediols and silanetriols see the following and references cited therein Chandrasekhar, V. Boomishankar, R. Nagendran, S. Chem. Rev. 2004, 104, 5847. 

In addition to these requirements related to substrate structure, an ary] donor capable of undergoing transmetalation with Pd(II) intermediates under conditions suitable for C-H bond activation is necessary. Among the Ph-BX2/Ph-SiX3/ Ph-SnX3 trio, silanols have the desired reactivity. Although monophenyl silanol, silanediol, and silonate can be used as the aryl group donor, diphenylsilanol proved superior. 

Novel Metallo-Silanols, -Silanediols, and -Silanetriols of the Iron and Chromium Group ... 

The surface of silica is composed of silanols, =Si—OH, and siloxane bridges, =Si—O—Si=. Several different types of silanols can be distinguished spectroscopically single silanols versus geminal silanols (silanediols), and bridged silanols versus lone silanols ... 

As previously demonstrated, dimethyldioxirane is a mild and selective oxidizing reagent for the conversion of Si-H-functionalized organo- or metallo-silanes to the corresponding silanols [3b, 6]. This method was applied to generate the ferriomethyl-substituted silanols, silanediols and silanetriols 4a-c from 3a-c in acetone at -78°C (Scheme 1, route a). Additionally, 4a,b were prepared by hydrolysis of the ferriomethylchlorosilanes 5a,b in diethyl ether at 0°C in the presence of the auxiliary base EtsN (Scheme 1, route b). 

Scheme 7.19 Comparison of the cross-coupling reactions of silanols, silanediols, and silanetriols.

Organosilanols are analogous to alcohols the most common are simple silanols of the type R3SiOH, but compounds of the types R2Si(OH)2, silanediols, and RSi(OH)3, silanetriols, are also well known. Between... 

As already briefly mentioned, the oxygen-atom insertion into Si—H bonds of silanes constitutes a selective method for the chemoselective preparation of silanols, which has been much less studied compared to the CH oxidation. This unique oxyfunctionalization of silanes is also highly stereoselective (equation 35) since, like the CH insertions, it proceeds with complete retention of configuration. A novel application of the SiH insertion process is the synthesis of the unusual iron complex with a silanediol functionality, in which selectively both Si—H bonds of the silicon atom proximate to the iron ligand are oxidized in the silane substrate (equation 36). ... 

The condensation reactions of silanols are catalyzed by acids [19, 25-27,63—68, 72], Grubb measured the hydrogen chloride catalyzed silanoi condensation reaction of trimethylsilanol in methanol [19]. Lasocki and Michalska studied the effect of acid type on the condensation of dialkylsilanediols in dioxane [68]. Under anhydrous conditions, the rate of acid catalysis by strong acids (such as hydrogen bromide and perchloric acid) was directly related to the acid concentrations. The catalytic effects of weaker acids, such as hydrogen chloride, were not linearly related to the concentration. They postulated that in anhydrous dioxane, the strong acids were completely ionized while the weaker acids were not [68]. When small amounts of water were added to the solvent, all the acids behaved in a similar manner. Lasocki [64-67] extended the studies to examine the effects of alkyl or aryl substitution of silanediols on the condensation rate in aqueous dioxane [64-67]. The rate constants for acid catalyzed condensation of... 

A recent study of the photolysis of simple diazoalkanes 314 or diazirines 315, compounds known to lead to the formation of silenes under inert conditions, led, in oxygen-doped argon matrices, via the silene 316 to the siladioxirane 317. While previously postulated as an intermediate in silene oxidations, this is important experimental evidence for this intermediate. Continued photolysis of the system led to a compound identified as the silanone-formaldehyde complex 318, which on further irradiation led to the silanol-aldehyde 319. The latter compound itself underwent further photochemical oxidation leading to the silanediol 320160. The reactions are summarized in Scheme 58. Detailed infrared studies, including the use of isotopes, and calculations, were used to establish the structures of the compounds. 

Silanediol, diphenyl-, 3 62 Silanol, trimethyl-, formation of, by hydrolysis of hexamethyl-disilazane, 5 58... 

Molecules with silanol functions are known to form supramolecular arrays in the solid state (linear polymeric chains, 2D-sheets or layers, 3D-networks) based on intermolecular H-bonding between Si-OH groups like the one described in Scheme 4 for dialkyl-silanediol [18],... 

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