Silicon—platinum bonds reactions with

Platinum-silicon bonds may be made by the reaction of trans-[PtH(ClXPMe2Ph)2] with R3SiH in the presence of solvent, provided that R is an electron-withdrawing group such as Cl or aryl. For Cl3SiH reaction occurs at RT but for triarylsilanes at 80-90°C ... 

Chen et al. utUized a direct chemical reaction with a given solution (wet treatment) to modify the surface of the silicone rubber. The presence of a layer of PEO on a biomaterial surface is accompanied by reductions in protein adsorption, and cell and bacterial adhesion. In order to obtain a PEO layer on top of the silicone rabber surface, the surface was firstly modihed by incorporating an Si-H bond using (MeHSiO) , and followed by PEO grafting to the surface using a platinum-catalyzed hydrosilylation reaction. These PEO-modified surfaces were demonstrated by fibrinogen adsorption both from buffer and plasma, as well as albumin adsorption from buffer. Reductions in protein adsorption of as much as 90% were noted on these surfaces. 

Si-H bonds add across olefins over platinum catalysts. This reaction (hydrosi-lation) is used in silicone polymer manufacture, when the silane is a hydrogen bearing oligo(alkylsiloxane). With some types of olefin there have been reports of runaways to explosion because of unexpectedly fast reaction. Dangerous substrates recorded are 2-allylphenols and ethenylsiloxanes. Very low levels of catalyst (ppm) and good cooling are recommended. 

In the last few years the design and use of various disilane compounds has gained importance because of the reactivity of the Si-Si bond and the large potential for organic synthesis involved with it. Many publications offer us numerous examples of possible reactions at the silicon-silicon bond such as addition reactions with C-C double bonds or C-C triple bonds [1, 2], addition reactions with C-element multiple bonds (e.g. aldehydes, quinones, isocyanides) [3-5] or metathesis [6, 7] and cross-metathesis [8]. In the most cases the existence of a catalyst (palladium, platinum or nickel complexes) for activation of the silicon-silicon a bond is indispensable for a successful transformation [9-11]. 

Several observations led to the proposal that some of the catalysts containing metals other than platinum do not react by the Chalk-Harrod mechanism. First, carbon-silicon bond-forming reductive elimination occurs with a sufficiently small number of complexes to suggest that formation of the C-Si bond by insertion of olefin into the metal-silicon bond could be faster than formation of the C-Si by reductive elimination. Second, the formation of vinylsilane as side products - or as the major products in some reactions of silanes with alkenes cannot be explained by the Chalk-Harrod mechanism. Instead, insertion of olefin into the M-Si bond, followed by p-hydrogen elimination from the resulting p-silylalkyl complex, would lead to vinylsilane products. This sequence is shown in Equation 16.39. Third, computational studies have indicated that the barrier for insertion of ethylene into the Rh-Si bond of the intermediate generated from a model of Wilkinson s catalyst is much lower than the barrier for reductive elimination to form a C-Si bond from the alkylrhodium-silyl complex. ... 

X-ray crystallography. The observation that our platinum-silicon 4MR can be formed from reagents with Si-Si single bonds is also consistent with the P2 h bonding description. West has prepared monoplatinum complexes of disilenes from disilenes or disilanes by three routes. One route, which is similar to the reaction depicted in Eg.4, is shown in Eg.5. The platinum disilene complexes are described by the two resonance forms drawn in Eg.5. (It is interesting to note that oligomeric silanes are obtained as by-products of Eg.5.)... 

This reaction is catalyzed by a platinum catalyst such as Speier s catalyst, chloroplatinic acid. Because the catalyst also isomerizes the terminal double bond, the reaction maybe run with an excess of vinyl to make sure all the reactive sites on the silicone are reacted. SiH also reacts with ROH and, for this reason, alkoxy end-capped polyethers maybe preferred. Alkoxy end-capped polyethers are also useful when the surfactant will be used in a chemically reactive system such as polyurethane foam manufacture. 

Fig. 8.3 Warren R. Roper (born in 1938) studied chemistry at the University of Canterbury in Christchurch, New Zealand, and completed his Ph.D. in 1963 under the supervision of Cuthbert J. Wilkins. He then undertook postdoctoral research with James P. Collman at the University of North Carolina at Chapel Hill in the US, and returned to New Zealand as Lecturer in Chemistry at the University of Auckland in 1966. In 1984, he was appointed Professor of Chemistry at the University of Auckland and became Research Professor of Chemistry at the same institution in 1999. His research interests are widespread with the emphasis on synthetic and structural inorganic and organometallic chemistry. Special topics have been low oxidation state platinum group metal complexes, oxidative addition reactions, migratory insertion reactions, metal-carbon multiple bonds, metallabenzenoids and more recently compounds with bonds between platinum group metals and the main group elements boron, silicon, and tin. His achievements were recognized by the Royal Society of Chemistry through the Organometallic Chemistry Award and the Centenary Lectureship. He was elected a Fellow of the Royal Society of New Zealand and of the Royal Society London, and was awarded the degree Doctor of Science (honoris causa) by the University of Canterbury in 1999 (photo by courtesy from W. R. R.)...

A first approach to obtain silicon-containing surfactants without Si-0 bonds was made by Dow Corning [4, 5]. They reacted carbosilanes with several a-olefins containing reactive (e g., epoxy-fiinctional) moieties, catalyzed by platinum complexes. The surfactant properties and high stabilities of these compounds indicated a promising solution. However, the corresponding carbosilanes as precursors were synthesized via a Grignard reaction, so these silane surfactants were difficult and costly to produce. 

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