Catalysis of hydrosilylation: Part XXIV. H2PtCl6 in cyclohexanone as hydrosilylation catalyst—what is the active species in this catalytic system?

A cyclohexanone solution of H2PtCl6 was examined to find the catalytic species responsible for the hydrosilylation of the olefinic C=C bond. Similarly to other H2PtCl6–solvent systems (e.g. Speier's and Karstedt's catalysts), the real catalyst appeared to be colloidal platinum formed in situ by stepwise reduction [Pt(IV)Pt(O)] and dechlorination of the platinum precursor. The role of cyclohexanone seems to be to form sufficiently stable platinum complexes to avoid rapid platinum precipitation and aggregation. The studies of H2PtCl6–solvent systems are of practical importance since these compounds are widely used catalyst precursors for hydrosilylation on an industrial scale.

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