Applications of Karstedt Catalysts

Karstedt's catalyst is an organoplatinum compound derived from divinyl-containing disiloxane. This coordination complex is widely used in hydrosilylation catalysis. It is a colorless solid that is generally assumed to be a mixture of related Pt(0) alkene complexes.The catalyst is named after Bruce D. Karstedt, who developed it in the early 1970s while working for General Electric.

Structure

The oxidation state of the platinum is 0. Using X-ray crystallography, the structure of Pt2[(Me2SiCH=CH2)2O]3 has been confirmed. Each Pt(0) center is surrounded by three alkene ligands provided by three 1,1,3,3-tetramethyl-1,3-divinyldisiloxane ligands. The Pt center and six coordinated carbon atoms are approximately coplanar, as found for simpler complexes such as Pt(C2H4)3.

Application

Karstedt catalysts promote a quick, low temperature curing of the hydrosilylation reaction. They form silicone elastomers through an addition curing cross-linking reaction between Si-vinyl and Si-H groups. The fast cure version is a high activity form of Karstedt catalyst promoting rapid curing under ambient conditions, used to cross-link silicone polymers in two-part RTV silicone systems.

Karstedt's catalyst [Ptn(H2C=CHSiMe2OSiMe2CH=CH2)m] is a kind of platinum catalyst which is widely used in the hydrosilylation.  Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex is a platinum complex, commonly known as a Karstedt′s catalyst. It is generally employed as a catalyst in hydrosilylation reactions. In the catalyst, platinum is in the zero oxidation state with no co-ordinated chlorides.

Carbon-silicon bonds are often generated via hydrosilylation of alkenes. This reaction has very important applications to industry. While it is favorable thermodynamically, hydrosilylation does not proceed in the absence of a catalyst, such as Karstedt's catalyst. The catalyst is produced by treatment of chloroplatinic acid by the divinyltetramethyldisiloxane.

The catalyst can also be used in a reductive amination reaction between a carboxylic acid and an amine with phenylsilane as the reducing agent.