- Towards Naked Zinc(II) in the Condensed Phase: A Highly Lewis Acidic ZnII Dication Stabilized by Weakly Coordinating Carborate Anions
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The employment of the hexyl-substituted anion [HexCB11Cl11]? allowed the synthesis of a ZnII species, Zn[HexCB11Cl11]2, 3, in which the Zn2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1-hexene and 1-methyl-1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol?1) that is higher than that of the landmark Lewis acid B(C6F5)3 (FIA=220.5 kJ mol?1). This high Lewis acidity leads to a high activity in catalytic CO2 and Ph2CO reduction by Et3SiH and hydrogenation of 1,1-diphenylethylene using 1,4-cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, and DFT studies.
- Adet, Nicolas,Specklin, David,Gourlaouen, Christophe,Damiens, Thibault,Jacques, Béatrice,Wehmschulte, Rudolf J.,Dagorne, Samuel
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supporting information
p. 2084 - 2088
(2020/11/30)
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- Synthesis of the first persilylated ammonium ion, [(Me3Si) 3NSi(H)Me2]+, by silylium-catalyzed methyl/hydrogen exchange reactions
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This work describes the unexpected synthesis and characterization of the first persilylated ammonium ion, [(Me3Si)3NSi(H)Me 2]+, in the reaction of (Me3Si)3N with [Me3Si-H-SiMe3][B(C6F5) 4]. NMR and Raman studies revealed a transition-metal-free silylium ion catalyzed substituent redistribution process when [Me3Si-H- SiMe3]+ was used as the silylating reagent. These observations were affirmed in the reaction with [Et3Si-H-SiEt 3][B(C6F5)4]. A Lewis acid catalyzed scrambling process always occurs if an excess of silanes is present in the formation of silylium cations while employing the standard Bartlett-Schneider- Condon type reaction. Additionally, the thermodynamics of this process was accessed by DFT computations at the pbe1pbe/aug-cc-pVDZ level, indicating alkyl substituent exchange equilibria at the silane and preference of the formation of [(Me3Si)3NSi(H)Me2]+ over [(Me 3Si)4N]+.
- Labbow, Rene,Reiss, Fabian,Schulz, Axel,Villinger, Alexander
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supporting information
p. 3223 - 3226
(2014/08/05)
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- Gas-phase ion-molecular reactions of free ethylsilylium ions with ethylene
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Gas-phase reaction of ethylsilylium ions with ethylene was studied by the radiochemical method. The reaction occurs via excited adduct C4H11Si+ which structurally is a complex of ethylsilylium cation with ethylene. The lifetime of this complex is long enough for the isotope exchange between tritium atoms of the cation and a proton of ethylene, as well as the isomerization of ethylsilylium cation to dimethylsilylium to occur. Decomposition of the complex results in predominant formation of labeled ethylene.
- Shchukin,Kochina,Sinotova,Ignat'ev
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p. 206 - 209
(2007/10/03)
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- Ion-molecule reactions of monosubstituted ethylsilylium ions with trimethyl(tert-butylamino)silane in the gas phase
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Reaction of nuclear-chemically generated ethylsilylium ions with trimethyl(rert-butylamino)silane in the gas phase was studied. In the course of reaction the ethylsilylium ion completely isomerizes into the dimethylsilylium ion. Experiments show that the pathway involving proton transfer practically is not realized, in contrast to the reactions of carbenium ions with amines.
- Kochina,Shchukin,Nefedov,Sinotova
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p. 1233 - 1236
(2007/10/03)
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