Dyotropic rearrangement of organosilylenium ions in the gas phase

Bakhtiar, Ray; Holznagel, C. M.; Jacobson, D. B.

doi:10.1021/om00027a043

Cited by 24 publications

(30 citation statements)

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“…In a similar fashion, it was suggested that [(Me) 3 Si] + isomerizes into [EtMeSiH] + prior to collision‐induced loss of C 2 H 4 10. Both isomers differ substantially in their reactivity towards C 2 D 4 and CH 3 OH 13.…”

Section: Introductionmentioning

confidence: 87%

“…The literature reveals that even‐electron organosilicon cations frequently undergo complex rearrangements 7–10. For example, the dominant metastable process for [(Me) 3 Si] + is loss of C 2 H 4 7.…”

Section: Introductionmentioning

confidence: 99%

“…Interconversion between these two isomers was observed to be very slow, but it could be induced by gentle collisional activation 9. CID of 13 C‐labeled compounds indicated that [(Me) 2 SiH] + isomerizes into [EtSiH 2 ] + prior to loss of C 2 H 4 , the dominant CID process 10. It was suggested that a concerted 1,2‐hydrogen—1,2‐methyl migration (a dyotropic rearrangement11) occurs.…”

Section: Introductionmentioning

confidence: 99%

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Metastable and collision-induced fragmentation studies and thermochemistry of isomeric C4H11Si+ ions and their adducts with C4H12Si silanes

et al. 2000

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Metastable Ion (MI) and collision-induced dissociation (CID) mass spectra for all isomeric even-electron [C(4)H(12)Si - H](+) ions were recorded and compared. Deuterium labeling experiments indicated that most precursors give rise to silylium ions. Silylium ions with two or more methyl groups are found to lose C(2)H(4) after isomerization via a straightforward hydrogen transfer to the appropriate ethylsilylium ion. Similarly, all isomeric propyl- and butyl-containing silylium ions are found to lose C(2)H(4) by rearrangement preceding dissociation. In the CI source of the mass spectrometer many of the silylium ions are found to cluster with the parent neutral silane present in the source to give stable [M - H](+)+M adduct ions. The MI and CID spectra of these adduct ions were also obtained. In the MI spectra of all adducts, except i-BuSiH(3), only the starting silylium ion is observed. Under CID conditions generation of silylium ions dominates. Deuterium labeling studies show that this dissociation may be accompanied by some rearrangement, in particular for the adducts from i-BuSiH(3). High-pressure mass spectrometric clustering equilibrium measurements were also carried out to determine the enthalpies and entropies of binding of the silylium ions to the neutral silanes. These measurements yield insight into the effects of various alkyl group substitutions on the association thermochemistry in these adducts. Copyright 2000 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Metastable and collision-induced fragmentation studies and thermochemistry of isomeric C4H11Si+ ions and their adducts with C4H12Si silanes

et al. 2000

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“…To the best of our knowledge there were no attempts to analyze the mechanisms of rearrangements and fragmentation for germylium or stannylium cations, although there exists numerous experimental [3][4][5][6][7][8][9]13] and theoretical [4,[10][11][12][13][14] studies of similar processes for silylium ions. However in these studies no attention was paid to the possibility of formation of the ''side-on" structures, which in the case of cations containing methyl groups manifest themselves as complexes with alkanes.…”

Section: Introductionmentioning

confidence: 99%

Rearrangement and decomposition of (CH3)3M+ (M=Si, Ge, Sn) ions: A DFT study

Ignatyev

Sundius

2008

Journal of Organometallic Chemistry

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“…However, the different yields of silylation of ethyland diethylsilylium ions is explained by the different ability of these ions to isotope exchange with ipsohydrogen atoms of benzene: The former ion is much more reactive [28,29]. Therefore, with the diethylsilylium ion, the monomolecular decomposition of the complex results in preferential formation of tritium-free benzene (the radiochemical method detects labeled reaction products only).…”

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confidence: 99%

Effect of the Electronic Structure of Carbenium and Silylium Ions on Their Chemical Behavior

2005

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Being isoelectronic analogs, silylium and carbenium ions exhibit quite a different reactivity toward nucleophiles. This is explained by their different electronic structures and charge distributions: In silylium ions the positive charge is almost completely concentrated on the silicon atom, and hydrogen atoms on the cationic center are hydride in nature, wheteas in carbenium ions, the positive charge is uniformly distributed between the carbenoid center and hydrogen atoms. Carbenium ions R 3 C + and their isoelectronic analogs, silylium ions R 3 Si + (R = H, Alk), are shortlived reactive intermediates whose properties determine the mechanism and direction on many chemical reactions. Therefore, transformations of these cations attract enduring researcher's attention. The role of carbenium ions in organic chemistry is well-known: They take part in most reactions. The information on reactions of silylium ions has long been very scarce, and these ions have long been considered to behave similarly to carbenium ions. In earlier works silylium ions have even been postulated as intermediates in many organosilicon reactions, such as catalytic disproportionation of alkylchlorosilanes [133]. However, no clear evidence to show that silylium ions are involved in such reactions has not been provided.The problem is made even more intricate by the fact that silylium ions are impossible to detect in condensed media, even though they are thermodynamically more stable and easier formed in the gas phase compared with carbenium ions. Gas-phase reactions of silylium ions with nucleophiles have been studied mostly by mass spectrometry and ioncyclotron resonance, and these studies focused on the observation of adducts, i.e. complexes of the ions with nucleophiles. These studies gave estimates for the reactivity of silylium ions but gave no idea of the direction and mechanisms of the overall reactions. Thus, traditional methods for generation, observation, and study of carbenium ions proved absolutely unsuitable for silylium ions.In [4,5] we proposed a unique nuclear chemical technique for generation of silylium ions of the desired composition and structure (with a preset charge localization) in the gas and condensed phases. This technique is based on b-decay of tritium incorporated in substituted silanes. R 43n SiT n 76 [R 43n SiT n31 He] + 76 R 43n Si + T n31 + He. b !Reactions of thus generated silylium ions with nucleophiles have been studied by the radiochemical method that allows observation of neutral reaction products, including isomers.Previously we performed a radiochemical study of ion3molecule reactions of ethyl-and diethylsilylium ions with benzene [638], alcohols [9][10][11], and organic [12] and organosilicon [13] ethers and amines [14,15] in the gas and condensed phases. We suggested mechanisms of these reactions and revealed features that distinguish them from reactions of carbenium ions. Of special mention are reactions of silylium ions with organosilicon amines and benzene. It is these reactions that the differences in...

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Dyotropic rearrangement of organosilylenium ions in the gas phase

Cited by 24 publications

References 0 publications

Metastable and collision-induced fragmentation studies and thermochemistry of isomeric C4H11Si+ ions and their adducts with C4H12Si silanes

Metastable and collision-induced fragmentation studies and thermochemistry of isomeric C4H11Si+ ions and their adducts with C4H12Si silanes

Rearrangement and decomposition of (CH3)3M+ (M=Si, Ge, Sn) ions: A DFT study

Effect of the Electronic Structure of Carbenium and Silylium Ions on Their Chemical Behavior

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