Gas-phase reactions of anions with substituted silanes

DePuy, Charles H.; Bierbaum, Veronica M.; Flippin, Lee A.; Grabowski, Joseph J.; KING, G. K.; Schmitt, Robert J.; SULLIVAN, S. A.

doi:10.1021/ja00535a031

Cited by 121 publications

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“…Fluorideinduced desilylation is found to be thermochemically allowed with all of the silanes examined in this work, albeit marginally for ethoxytrimethylsilane. Therefore, alkoxide ion formation by fluoride-induced desilylation is shown to be thermochemically viable, consistent with the observed reactivity [7]. Similarly, the difference between the FA of tetramethylsilane and the FSi(CH 3 ) 3 affinity of methide is ϳ13 kcal/mol, consistent with the observation that the only observed reactions between fluoride and TMS are adduct formation (94%) and proton transfer (6%) [7].…”

Section: Discussionsupporting

confidence: 80%

“…Therefore, alkoxide ion formation by fluoride-induced desilylation is shown to be thermochemically viable, consistent with the observed reactivity [7]. Similarly, the difference between the FA of tetramethylsilane and the FSi(CH 3 ) 3 affinity of methide is ϳ13 kcal/mol, consistent with the observation that the only observed reactions between fluoride and TMS are adduct formation (94%) and proton transfer (6%) [7]. Damrauer and co-workers have previously addressed the general importance of the balance between the affinity of the silane to the incoming anion and the leaving group [29].…”

Section: Discussionsupporting

confidence: 76%

“…Fluoride-induced desilylation is particularly useful because the formation of the strong SiOF bond is a highly selective procedure [1]. In the gas phase, fluoride-induced desilylation, pioneered by DePuy et al [6,7], is also very functional and has been used extensively to generate carbanions regioselectively via the general reaction shown in eq 1.…”

mentioning

confidence: 99%

“…In particular, fluoride-induced desilylation has been used to generate various cyclic [8,9] and alkenyl ions [10] in the gas phase, and overviews of the reactivity are available [7,11]. By using the reaction of fluoride with silanes, Kass and coworkers have prepared several anions for characterization, including acetamide enolate [12], cyclopropenyl derivatives [8,13], and cubyl anion [14].…”

mentioning

confidence: 99%

“…However, because third row and lower main-group elements (e.g., P, S, Cl) readily undergo hypervalent bonding [24], the pentavalent siliconate is a stable intermediate in the reaction and can, in many cases, be observed [25][26][27][28]. Because of their stability, siliconates are often used in fundamental studies of hypervalency [26, 29 -32], as well as in numerous theoretical [33,34] and experimental [7,29,[35][36][37][38][39][40] studies.…”

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confidence: 99%

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Fluorotrimethylsilane affinities of anionic nucleophiles: A study of fluoride-induced desilylation

Krouse

Wenthold

2005

J. Am. Soc. Mass Spectrom.

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In this study, preparation and decomposition of five novel pentavalent fluorosiliconates, RSi(CH 3 ) 3 F Ϫ (R ϭ CH 3 CH 2 O, CF 3 CH 2 O, (CH 3 ) 2 CHO, (CH 3 ) 3 SiO, and (CH 3 ) 3 SiNH) is used to investigate the process of fluoride-induced desilylation. The siliconates were characterized by collision-induced dissociation and energy-resolved mass spectrometry. Decomposition of RSi(CH 3 ) 3 F Ϫ leads to loss of the nucleophile R Ϫ and FSi(CH 3 ) 3 , except in the case of (CH 3 ) 3 SiNHSi(CH 3 ) 3 F Ϫ , where HF loss is also observed. Ion affinities for FSi(CH 3 ) 3 have been measured for all five nucleophiles, and compare well with computational predictions. The observed trend of the bond dissociation energies resembles the trend of ⌬H acid values for the corresponding conjugate acids, RH. Additionally, this data has been incorporated with existing thermochemistry to derive fluoride affinities for four of the silanes (R ϭ CH 3 CH 2 O, (CH 3 ) 2 CHO, (CH 3 ) 3 SiO, and (CH 3 ) 3 SiNH). We use the fluoride affinity of the silanes and the FSi(CH 3 ) 3 affinity of the departing nucleophilic anion to assess the feasibility of fluorideinduced desilylation of the silanes examined in this work. (J Am Soc Mass Spectrom 2005, 16, 697-707)

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Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 76%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Fluorotrimethylsilane affinities of anionic nucleophiles: A study of fluoride-induced desilylation

Krouse

Wenthold

2005

J. Am. Soc. Mass Spectrom.

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Potential interstellar molecules. Formation of neutral C6CO from C6CO?� in the gas phase

Dua

Blanksby

Bowie

2000

Rapid Commun. Mass Spectrom.

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Computations at the RCCSD(T)/aug-cc-pVDZ//B3LYP/6-31G* level of theory indicate that neutral C(6)CO is a stable species. The ground state of this neutral is the singlet cumulene oxide :C=C=C=C=C=C=C=O. The adiabatic electron affinity and dipole moment of singlet C(6)CO are 2.47 eV and 4.13 D, respectively, at this level of theory. The anion (C(6)CO)-* should be a possible precursor to this neutral. It has been formed by an unequivocal synthesis in the ion source of a mass spectrometer by the S(N)2(Si) reaction between (CH(3))(3)Si-C(triple bond)C-C(triple bond)C-C(triple bond)C-CO-CMe(3) and F(-) to form (-)C(triple bond)C-C(triple bond)C-C(triple bond)C-CO-Me(3) which loses Me(3)C* in the source to form C(6)CO(-)*. Charge stripping of this anion by vertical Franck-Condon oxidation forms C(6)CO, characterised by the neutralisation-reionisation spectrum (-NR(+)) of C(6)CO(-*), which is stable during the timeframe of this experiment (10(-6) s).

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The Electrophilic Substitution of Allylsilanes and Vinylsilanes

1989

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Allylsilanes and vinylsilanes usually react with electrophiles to give substitution. These reactions are conveniently understood as the reactions of alkenes that have been significantly but only slightly modified by the presence of the silyl group. In both reactions, substitution is favored over addition, and both the site of attack and the site of the double bond in the product are usually determined by the site of the silyl group in the starting material. In this chapter only the electrophilic substitution reactions of allylsilanes, vinylsilanes, and allenylsilanes is discussed. It is further restricted to the reactions of tetraorganosilanes because they are synthetically the most interesting in the laboratory. However, although they are not included in the tables, allylsilanes and vinylsilanes that react by addition rather than substitution or that are not tetraorganosilanes are referred to occasionally in the text wherever their reactions illuminate the discussion. Many of the features of the reactions discussed here are shared by the reactions of arylsilanes, ethynylsilanes, propargylsilanes, cyclopropylsilanes, and cyclopropylmethylsilanes. The methods by which allylsilanes and vinylsilanes are synthesized have been summarized in several places. Stereochemsitry of reactions of allenylsilanes and vinylsilanes is discussed. Scope and limitations include discussions of protodesilylation and deuterodesilyation and the use of carbon, nitrogen, and oxygen as electrophiles. Other electrophiles include phosphorus, sulfur, metals, halogens, and selenium. All of these are covered in the extensive tabular material

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Gas-phase reactions of anions with substituted silanes

Cited by 121 publications

References 0 publications

Fluorotrimethylsilane affinities of anionic nucleophiles: A study of fluoride-induced desilylation

Fluorotrimethylsilane affinities of anionic nucleophiles: A study of fluoride-induced desilylation

Potential interstellar molecules. Formation of neutral C6CO from C6CO?� in the gas phase

The Electrophilic Substitution of Allylsilanes and Vinylsilanes

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