- Silicon Tetrakis(trifluoromethanesulfonate): A Simple Neutral Silane Acting as a Soft and Hard Lewis Superacid
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A facile synthesis and isolation of pristine silicon tetrakis(trifluoromethanesulfonate), Si(OTf)4, is reported, acting as the first neutral silicon-based Lewis superacid suitable towards soft and hard Lewis bases. Its OTf groups have a dual function: they are excellent leaving groups and modulate the degree of reactivity towards soft and hard Lewis bases. Exposed to soft Lewis donors, Si(OTf)4 leads to [L2Si(OTf)4] complexes (L=isocyanide, thioether and carbonyl compounds) with retention of all Si?OTf bonds. In contrast, it can cleave C?X bonds (X=F, Cl) of hard organic Lewis bases with a high tendency to form SiX4 (X=F, Cl) after halide/triflate exchange. Most notable, Si(OTf)4 allows a gentle oxydefluorination of mono- and bis(trifluoromethyl)benzenes, resulting in the formation of the corresponding benzoylium species, which are stabilized by the weakly coordinating [Si(OTf)6] dianion.
- Driess, Matthias,Hermannsdorfer, André
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supporting information
p. 13656 - 13660
(2021/05/03)
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- Synthesis and structure of tritylium salts
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Several tritylium compounds [Ph3C][A] have been isolated by salt metathesis or halide abstraction reactions starting from Ph3C-X (X = halogen) and Lewis acids in good yields (A = BF4, BCl4, AlCl4, GaCl4, PF6, AsF6, SbF6, SbCl6, CHB11H5Cl6, CHB11Cl11, CHB11H5Br6, CF3COO, CF3SO3, N3). The structures of 15 tritylium salts bearing different types of weakly coordinating anions (A-) have been determined. The structures are discussed on the basis of ion pairing versus covalent bond formation and solid-state interactions in comparison with gas-phase data.
- Hinz, Alexander,Labbow, René,Rei?, Fabian,Schulz, Axel,Sievert, Katharina,Villinger, Alexander
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p. 1641 - 1650
(2015/10/28)
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- Triflyloxy-substituted carboranes as useful weakly coordinating anions
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New carborane anions carrying one or three triflyloxy substituents are described. The mono-triflyloxy substituted carborane can be halogenated to give pentabromo and decachloro derivatives with preservation of the B-OTf linkage. The use of [HCB11Cl10OTf]- as a weakly coordinating anion is demonstrated.
- Press, Loren P.,Mcculloch, Billy J.,Gu,Chen,Foxman,Ozerov, Oleg V.
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supporting information
p. 14034 - 14037
(2015/09/15)
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- Charge delocalization and enhanced acidity in tricationic superelectrophiles
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This Article presents the results from studies related to the chemistry of tricationic superelectrophiles. A series of triaryl methanols were ionized in Bronsted superacids, and the corresponding tricationic intermediates were formed. The trications are found to participate in two types of reactions; both are characteristic of highly charged organic cations. One set of reactions occurs through charge migration. A second set of reactions occurs through deprotonation of an unusually acidic site on the tricationic species. One of the tricationic intermediates has been directly observed by low temperature NMR spectroscopy. These highly charged ions and their reactions have also been studied using density functional theory calculations. As a result of charge migration, electron density at a carbocation site is found to increase with progression from monocationic to pentacationic structures.
- Naredla, Rajasekhar Reddy,Zheng, Chong,Nilsson Lill, Sten O.,Klumpp, Douglas A.
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scheme or table
p. 13169 - 13175
(2011/10/08)
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- Trityl tetraphenylborate as a reagent in organometallic chemistry
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Trityl tetraphenylborate, prepared from trityl triflate and sodium tetraphenylborate, is shown to be a useful hydride and methyl anion abstraction reagent for organometallic compounds.It reacts with (η5-C5Me5)(PMe3)2RuMe to give the fulvene com
- Straus, Daniel A.,Zhang, Cheng,Tilley, T. Don
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p. C13 - C17
(2007/10/02)
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- The Oxidative Michael Reaction. A Highly Diastereoselective Synthesis of 5-Oxocarboxylic Acid Derivatives
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Methyldiphenylsilyl enol ethers react with an allylic cation stablized by two sulfur atoms in a highly anti-selective manner to afford 5-oxocarboxylic acid derivatives.
- Hashimoto, Yukihiko,Mukaiyama, Teruaki
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p. 1623 - 1626
(2007/10/02)
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