The stability of bridgehead and rigid tertiary carbenium ions in the gas phase and their rate of formation in solvolysis reactions

Mueller, P.; Milin, Didier; Feng, W. Q.; Houriet, R.; Della, Ernest W.

doi:10.1021/ja00041a039

Cited by 24 publications

(8 citation statements)

References 3 publications

(4 reference statements)

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“…Over the past 7 years, we have obtained experimental data for the stabilities of bridgehead carbenium ions in the gas phase by several methods. A first set of data was obtained by measuring the gas-phase basicity of olefins or the equilibrium constants for bromide exchange between cations by ICR techniques . More recently, Abboud et al reported that dissociative proton attachment (DPA) may be used to generate carbenium ions from halides and alcohols under mild conditions and measure their stability .…”

Section: Introductionmentioning

confidence: 99%

The Stability of Bridgehead Carbocations

et al. 1999

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The gas-phase stability of bridgehead carbocations has been determined by Fourier transform ion cyclotron resonance spectroscopy (FT ICR) based on dissociative proton attachment (DPA) of bridgehead bromides, chlorides, and alcohols. When appropriate leaving group corrections are applied, the relative ion stabilities obtained from these precursors are identical. The relative rate constants (log k) for solvolysis of bridgehead derivatives correlate with the stabilities of the cations over the entire reactivity range. Theoretical calculations of the stabilities of the ions relative to those of the respective hydrocarbons at the MP2/6-311G** level agree fully with the experimental data

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Section: Introductionmentioning

confidence: 99%

The Stability of Bridgehead Carbocations

et al. 1999

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“…They refer to average values for bromides. 3,4 Figure 1 shows that the ICR data collected from olefin protonation (filled circles) are in reasonable agreement with the DPA line, although there is some scatter. 7 The ICR data for bromide exchange are in column 4.…”

Section: Introductionmentioning

confidence: 56%

“…Early empirical force-field calculations have been used to rationalize the structural effects on the rate constants of solvolysis in terms of strain changes between the bridgehead compound and the developing carbenium ion, which was assumed to be close to the transition state of the reaction in terms of energy and structure. 3,4 The observation of rearrangements occurring during the ICR experiments casts doubt on the entire set of data obtained by this method. In order to remedy this situation, we determined the stability of bridgehead-and bridgehead-like tertiary carbenium ions by ion cyclotron resonance (ICR) techniques.…”

Section: Introductionmentioning

confidence: 99%

“…All energies are expressed as Gibbs free energies in kcal mol À1 (1 kcal = 4.184 kJ) relative to 1-adamantyl according to Eqn. Enthalpies of formation of the carbenium ions can be calculated provided the enthalpies of formation of the olefins are known [DH f o (MH ) 3,4 Originally, the ICR data were reported as enthalpies and are, therefore, not strictly comparable to the DPA results in column 3. The DPA data in column 3 are from Ref.…”

Section: Introductionmentioning

confidence: 99%

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Gas-phase stability of tertiary carbenium ions and rates of solvolysis of tertiary derivatives

Müller

Rossier

Abboud

2000

J. Phys. Org. Chem.

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“…Schleyer and co-workers 29 in late 70's and Mueller et al 30 in early 90's postulated that 90% of the carbocation character is developed in the solvolysis transition states, which could contradict the aforementioned Winstein's hypothesis. 26 As a consequence of early conclusions from Schleyer and co-workers 29 and those from Mueller et al…”

Section: Introductionmentioning

confidence: 98%

Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

Firme¹

2012

J. Braz. Chem. Soc.

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A assistência da deslocalização de elétrons sigma ou assistência anquimérica dos elétrons sigma explica grandes diferenças de velocidade na solvólise de 2-exo-e 2-endo-norbornilp-bromobenzenosulfonatos. Este estudo foi anteriormente analisado pela teoria dos orbitais moleculares em fase gás. Ao revisitar este antigo problema a partir da teoria quântica de átomos em moléculas (QTAIM), novas informações sobre essas reações foram obtidas. Os resultados de QTAIM mostram que, na primeira etapa da solvólise não assistida nucleofilicamente dos alcoóis protonados 2-exo-norbornanol e 2-endo-norbornanol, ambas as reações são anquimericamente assistidas pela participação de elétrons sigma. Similarmente, na primeira etapa da solvólise não assistida nucleofilicamente dos álcoois protonados 2-endo-oxabicicloheptanol e 2-exooxabicicloheptanol, os resultados de QTAIM mostram que ambas as reações são anquimericamente assistidas: a primeira a partir da participação da ligação sigma C-O e de pares de elétrons isolados do oxigênio e a última a partir da participação da ligação sigma C1-C2. The assistance of s electron delocalization or anchimeric assistance of s electrons accounts for the large rate differences in the solvolysis of 2-exo-and 2-endo-norbornylp-bromobenzenesulfonates. This study was formerly analyzed by molecular orbital theory in gas phase. By revisiting this old problem from the quantum theory of atoms in molecules (QTAIM), new information on these reactions was obtained. The QTAIM results show that, in the first step of the nucleophilically unassisted solvolysis of protonated 2-exo-norbornanol and of protonated 2-endo-norbornanol, both reactions are anchimerically assisted by sigma bond participation. Similarly, in the first step of the nucleophilically unassisted solvolysis of protonated 2-endooxabicycloheptanol and of protonated 2-exo-oxabicycloheptanol, the QTAIM results show that both reactions are anchimerically assisted: the former from sigma bond participation from O-C bonds and valence shell electron participation from oxygen atom and the latter from sigma bond participation from C1-C2 bond.

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The stability of bridgehead and rigid tertiary carbenium ions in the gas phase and their rate of formation in solvolysis reactions

Cited by 24 publications

References 3 publications

The Stability of Bridgehead Carbocations

The Stability of Bridgehead Carbocations

Gas-phase stability of tertiary carbenium ions and rates of solvolysis of tertiary derivatives

Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

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