A Janus‐Headed Lewis Superacid: Simple Access to,and First Application of Me3Si‐F‐Al(ORF)3 |
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| Authors: | Dipl‐Chem Michael Rohde Dr Lutz O Müller Dr Daniel Himmel Dr Harald Scherer Prof?Dr Ingo Krossing |
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| Institution: | Institut für Anorganische und Analytische Chemie, Freiburger Materialforschungszentrum (FMF) and Freiburg Institute for Advanced Studies (FRIAS), Section Soft Matter Science, Universit?t Freiburg, Albertstrasse 19, 79104 Freiburg (Germany) |
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| Abstract: | Upon reaction of gaseous Me3SiF with the in situ prepared Lewis acid Al(ORF)3, the stable ion‐like silylium compound Me3Si‐F‐Al(ORF)3 1 forms. The Janus‐headed 1 is a readily available smart Lewis acid that differentiates between hard and soft nucleophiles, but also polymerizes isobutene effectively. Thus, in reactions of 1 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(ORF)3]– or (FRO)3Al‐F‐Al(ORF)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(ORF)3. Compound 1 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. |
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| Keywords: | density functional calculations Lewis acids nucleophiles silylium weakly coordinating anions |
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