Karstedt's catalyst
{{Chembox
| ImageFile = KartstedtCatalyst.png
| ImageSize = 360 px
| ImageAlt =
| IUPACName =
| OtherNames =
|Section1={{Chembox Identifiers
| CASNo = 11057-89-9
| PubChem = 10959889
| EC_number = 270-844-4
| ChemSpiderID = 9135105
| UNNumber = 1307
| StdInChI=1S/C8H18OSi2.Pt/c1-7-10(3,4)9-11(5,6)8-2;/h7-8H,1-2H2,3-6H3;
| StdInChIKey = RCNRJBWHLARWRP-UHFFFAOYSA-N
| SMILES = C[Si](C)(C=C)O[Si](C)(C)C=C.[Pt]
}}
|Section2={{Chembox Properties
| Formula = C24H54O3Pt2Si6
| MolarMass = 949.4 g/mol
| Appearance = colorless solid
| Density = 1.74 g/cm3
| MeltingPtC = 12 to 13
| MeltingPt_notes =
| BoilingPtC = 139
| Solubility = insoluble
}}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt = 86
| AutoignitionPt =
| GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|226|304|312|315|319|332|335|373}}
| PPhrases = {{P-phrases|210|260|280|301+310|305+351+338|370+378}}
}}
}}
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.{{cite journal|last1=Lewis|first1=Larry N.|last2=Stein|first2=Judith|last3=Gao|first3=Yan|last4=Colborn|first4=Robert E.|last5=Hutchins|first5=Gudrun|title=Platinum catalysts used in the silicones industry|journal=Platinum Metals Review|date=1997|volume=41|issue=2|pages=66–74|doi=10.1595/003214097X4126675|s2cid=53707148|url=http://www.platinummetalsreview.com/pdf/pmr-v41-i2-066-075.pdf|archive-date=2015-09-24|access-date=2014-09-30|archive-url=https://web.archive.org/web/20150924074432/http://www.platinummetalsreview.com/pdf/pmr-v41-i2-066-075.pdf|url-status=dead}}{{cite journal|last1=Stein|first1=Judith|last2=Lewis|first2=L. N.|last3=Gao|first3=Y.|last4=Scott|first4=R. A.|title=In Situ Determination of the Active Catalyst in Hydrosilylation Reactions Using Highly Reactive Pt(0) Catalyst Precursors|journal=Journal of the American Chemical Society|year=1999 |volume=121|issue=15|pages=3693–3703|doi=10.1021/ja9825377}} The catalyst is named after Bruce D. Karstedt, who developed it in the early 1970s while working for General Electric.{{ cite patent | country = US | number = 3775452 | status = Patent | title = Platinum complexes of unsaturated siloxanes and platinum containing organopolysiloxanes | pubdate = 1973-11-27 | fdate = 1971-04-28 | pridate = 1971-04-28 | inventor = Bruce D. Karstedt | assign1 = General Electric
}}
Applications
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.{{cite journal|doi=10.15227/orgsyn.075.0078|title=Synthesis of Chiral (E)-Crotylsilanes: [3R- and 3S-]-(4E)-Methyl 3-(Dimethylphenylsilyl)-4-Hexenoate|journal=Organic Syntheses|volume=75|page=78|year=1998|author=Richard T. Beresis, Jason S. Solomon, Michael G. Yang, Nareshkumar F. Jain, James S. Panek}}{{cite journal|doi=10.15227/orgsyn.073.0094|title=Regio- and Stereoselective Intramolecular Hydrosilylation of a-hydroxy Enol Ethers: 2,3-syn-2-Methoxymethoxy-1,3-Nonanediol|journal=Organic Syntheses|volume=73|page=94|year=1996|author=Kohei Tamao |author2=Yoshiki Nakagawa |author3=Yoshihiko Ito }}
The catalyst can also be used in a reductive amination reaction between a carboxylic acid and an amine with phenylsilane as the reducing agent.{{cite journal|last1=Sorribes|first1=Iván|last2=Junge|first2=Kathrin|last3=Beller|first3=Matthias|title=Direct Catalytic N-Alkylation of Amines with Carboxylic Acids|journal=Journal of the American Chemical Society|volume=136|issue=40|date=29 September 2014|pages=14314–14319|doi=10.1021/ja5093612|pmid=25230096}}
Structure and bonding
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.{{cite journal|last1=Hitchcock|first1=Peter B.|last2=Lappert|first2=Michael F.|last3=Warhurst|first3=Nicholas J. W.|title=Synthesis and Structure of arac-Tris(divinyldisiloxane) diplatinum(0) Complex and its Reaction with Maleic Anhydride|journal=Angewandte Chemie International Edition in English|year=1991 |volume=30|issue=4|pages=438–440|doi=10.1002/anie.199104381}}