Silanol bridged silanols

Treatment of highly sterically hindered iodosilanes with a silver salt in a solvent containing water has also been used successfully to prepare bulky silanols (Scheme 6). The introduction of the OH group seems to occur not only by hydrolysis of the silyl perchlorates formed, but also by reaction of the bridged silicocationic species that are formed as intermediates in this type of reaction (62). The reaction... 

Fig. 4 (a) Chemical structure of tetra-ethyl-ortho-silicate (TEOS). (b) Removal of two oxygen atoms from TEOS. (c) Mechanism depicting how TEOS chemisorbs onto silanol groups (Si-OH) on surface, (d) Formation of Si-O-Si bridges by elimination reactions with neighboring molecules. (Figure adapted from [40])... 

Spectrum 1 illustrates how the interaction with tetramethylbenzene (by hydrogen-bonding) shifts the silanol band in Beta to 3563 cm" and the bridging hydroxyls to even lower frequencies where overlapping absorption from hydrogen-bonded silanols make them difficult to detect In spectrum 1 the bands between 3100 and... 

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