A Janus‐Headed Lewis Superacid: Simple Access to, and First Application of Me3Si‐F‐Al(ORF)31. Issue 5 (16th January 2014)

• Record Type: Journal Article
• Authors: Rohde, Michael; Müller, Lutz O.; Himmel, Daniel; Scherer, Harald; Krossing, Ingo
• Is Part Of: Chemistry. Volume 20:Issue 5(2014)
• Page Start: 1218
• Page End: 1222
• Publication Date: 2014-01-16
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201303671
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Upon reaction of gaseous Me₃SiF with the in situ prepared Lewis acid Al(OR^F)₃, the stable ion‐like silylium compound Me₃Si‐F‐Al(OR^F)₃<bold>1</bold> forms. The Janus‐headed <bold>1</bold> is a readily available smart Lewis acid that differentiates between hard and soft nucleophiles, but also polymerizes isobutene effectively. Thus, in reactions of <bold>1</bold> with soft nucleophiles (Nu), such as phosphanes, the silylium side interacts in an orbital‐controlled manner, with formation of [Me₃SiNu]⁺ and the weakly coordinating [FAl(OR^F)₃]^– or [(^FRO)₃Al‐F‐Al(OR^F)₃]^– anions. If exchanged for hard nucleophiles, such as primary alcohols, the aluminum side reacts in a charge‐controlled manner, with release of FSiMe₃ gas and formation of the adduct R(H)OAl(OR^F)₃. Compound <bold>1</bold> very effectively initiates polymerization of 8 to 21 mL of liquid C₄H₈ in 50 mL of CH₂Cl₂ already at temperatures between −57 and −30 °C with initiator loads as low as 10 mg in a few seconds with 100 % yield but broad polydispersities.</p> </abstract>