Silicon ligands sulfoxides

Evidence for hypervalent intermediates in sulfur chemistry is less well established than in phosphoras and silicon chemistry. Racemization and reduction of sulfoxides each appear to go through hypervalent lO-S-4 sulfiirane intermediates. In addition, pathways for the reaction of sulfonium salts with organometallics involve plausible hypervalent intermediates (Scheme 7). Ligand coupling with retention of configuration is presumed to occur via a sulfinane intermediate... 

The inhibitors act as ligands, blocking the hydrosilylation reaction by coordination to the metal center, but vmder conditions employed for cure, they release the active catalyst. The numerous vmsaturated organic compounds, such as esters, alcohols, ketones, sulfoxides, phosphines, phosphites, nitriles, azodicarbonyl compounds, triazoline, dienes, amine N-oxides, hydroperoxides, and others, are known and have been reported as platinum catalyst inhibitors during the cure of silicon rubber through addition processes (3,4). The unsaturated diesters (e.g., maleates and fumarates) are the most important and commonly used platinum inhibitors in industrial curing processes and have been described in many articles and patents. 

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