Silylium ions in catalysis

Klare, Hendrik F. T.; Oestreich, Martin

doi:10.1039/c003097j

Cited by 203 publications

(118 citation statements)

References 111 publications

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“…Based on the above results we propose, that the mechanism of hydrosilane chlorination (Scheme ) is very similar to the one published previously for hydrosilane hydroxylation . A reaction of B(C 6 F 5 ) 3 with Ph 3 CCl generates the key catalytic species [Ph 3 C] + [ClB(C 6 F 5 ) 3 ] − , which in turn reacts with the hydrosilane to form a corresponding silylium species [R 3 Si] + [ClB(C 6 F 5 ) 3 ] − as was previously demonstrated for an analogous reaction of hydrosilanes with [Ph 3 C] + [B(C 6 F 5 ) 4 ] − . However, the species [R 3 Si] + [ClB(C 6 F 5 ) 3 ] − is proposed to be unstable as it consists of a strongly electrophilic silylium cation in combination with nucleophilic chlorine atom.…”

Section: Resultssupporting

confidence: 82%

B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

Šimarek

Lamač

Horáček

et al. 2018

Applied Organom Chemis

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A chlorination of tertiary (5 examples), secondary (3 examples) and primary (PhSiH3) hydrosilanes by Ph3CCl with a catalytic amount of B(C6F5)3 is presented. The reaction was substantially faster than its non‐catalyzed version. The chlorination of secondary hydrosilanes and PhSiH3 proceeded in a stepwise manner, which allowed selective isolation of chlorohydrosilanes. The mechanism of catalytic hydrosilane chlorination seems to be distinct to mainstream B(C6F5)3 catalyzed reactions involving hydrosilanes (i.e. activation of Si‐H bond by the R3Si‐‐H‐‐B (C6F5)3 adduct formation). Contrary, the present process is based on an instant formation of [Ph3C]+[ClB(C6F5)3]− from B(C6F5)3 and Ph3CCl, followed by a hydride transfer from particular hydrosilane to tritylium cation with a concomitant generation of unstable silylium cation compensated by borate anion [ClB(C6F5)3]−. Subsequent decomposition of this ionic species leads to the corresponding chlorosilane and recuperation of B(C6F5)3.

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Section: Resultssupporting

confidence: 82%

B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

Šimarek

Lamač

Horáček

et al. 2018

Applied Organom Chemis

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“…[426] Thei nsitu reaction between excess Et 3 SiH and [Ph 3 C][B(C 6 F 5 ) 4 ]g enerates as ilylium ion species that can catalytically hydrodefluorinate the alkyl CÀFbonds in aseries of benzotrifluorides at room temperature. Thef act that such fierce electrophiles can be employed as catalysts for organic transformations is atrue testament to the weakly coordinating nature of their supporting WCAs.…”

Section: Silylium Ions In Catalysismentioning

confidence: 99%

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

et al. 2018

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This Review gives a comprehensive overview of the most topical weakly coordinating anions (WCAs) and contains information on WCA design, stability, and applications. As an update to the 2004 review, developments in common classes of WCA are included. Methods for the incorporation of WCAs into a given system are discussed and advice given on how to best choose a method for the introduction of a particular WCA. A series of starting materials for a large number of WCA precursors and references are tabulated as a useful resource when looking for procedures to prepare WCAs. Furthermore, a collection of scales that allow the performance of a WCA, or its underlying Lewis acid, to be judged is collated with some advice on how to use them. The examples chosen to illustrate WCA developments are taken from a broad selection of topics where WCAs play a role. In addition a section focusing on transition metal and catalysis applications as well as supporting electrolytes is also included.

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“…[1][2][3] Classicalh ydrogen onium specieso fa ll three groups (H 4 E + with E = N, P, As, and Sb; [4,5] H 3 E + with E = O, S; [4,[6][7][8] H 2 E + with E = F, Cl) [9,10] were already reported. Ever since the pioneering silyliumi on work by the groups of Lambert, Reed, Oestreich, and Müller, [17][18][19][20][21] salts bearingh omoleptict rimethylsilyl substituted cations ([T 4 E] + with E = N, [22] P, and As; [23] [T 2 E] + with E = F-I [12] and T = Me 3 Si)h aveb een in the focus of main group chemistry,h owever,t here is hardly anythingk nown about persilylated chalconium ions of the type [T 3 E] + . Ever since the pioneering silyliumi on work by the groups of Lambert, Reed, Oestreich, and Müller, [17][18][19][20][21] salts bearingh omoleptict rimethylsilyl substituted cations ([T 4 E] + with E = N, [22] P, and As; [23] [T 2 E] + with E = F-I [12] and T = Me 3 Si)h aveb een in the focus of main group chemistry,h owever,t here is hardly anythingk nown about persilylated chalconium ions of the type [T 3 E] + .…”

Section: Introductionmentioning

confidence: 99%

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

Bläsing

Labbow

Michalik

et al. 2020

Chemistry A European J

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Attempts have been made to prepares alts with the labile tris(trimethylsilyl)chalconium ions, [(Me 3 Si) 3 E] + (E = O, S), by reacting[ Me 3 Si-H-SiMe 3 ][B(C 6 F 5 ) 4 ]a nd Me 3 Si[CB] (CB À = carborate = [CHB 11 H 5 Cl 6 ] À ,[ CHB 11 Cl 11 ] À )w ith Me 3 Si-E-SiMe 3 .I nt he reaction of Me 3 Si-O-SiMe 3 with [Me 3 Si-H-SiMe 3 ] [B(C 6 F 5 ) 4 ], al igand exchange was observed in the [Me 3 Si-H-SiMe 3 ] + cation leadingt ot he surprising formation of the persilylated [(Me 3 Si) 2 (Me 2 (H)Si)O] + oxonium ion in af ormal [Me 2 (H)Si] + instead of the desired [Me 3 Si] + transferr eaction. In contrast, the expected homoleptic persilylated [(Me 3 Si) 3 S] + ion was formed and isolated as [B(C 6 F 5 ) 4 ] À and [CB] À salt, when Me 3 Si-S-SiMe 3 was treated with either [Me 3 Si-H-SiMe 3 ] [B(C 6 F 5 ) 4 ]o rM e 3 Si[CB]. However, the addition of Me 3 Si[CB] to Me 3 Si-O-SiMe 3 unexpectedly led to the release of Me 4 Si with simultaneous formation of ac yclic dioxonium dicationo ft he type [Me 3 Si-mO-SiMe 2 ] 2 [CB] 2 in an anion-mediated reaction. DFT studies on structure, bonding and thermodynamicso f the [(Me 3 Si) 3 E] + and [(Me 3 Si) 2 (Me 2 (H)Si)E] + ion formation are presented as well as mechanistic investigationso nt he template-driven transformation of the [(Me 3 Si) 3 E] + ion into a cyclic dichalconium dication [Me 3 Si-mE-SiMe 2 ] 2 2 + . Scheme1.Synthesis of silylated chalconium salts with [B(C 6 F 5 ) 4 ] À as counterion (E = O, S; T= Me 3 Si, R = alkyl).

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Silylium ions in catalysis

Cited by 203 publications

References 111 publications

B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

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Silylium ions in catalysis

Cited by 203 publications

References 111 publications

B(C6F5)3 catalysis accelerates the hydrosilane chlorination by Ph3CCl

B(C6F5)3 catalysis accelerates the hydrosilane chlorination by Ph3CCl

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

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B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl