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Dimer radical cations of methyl chloride have been prepared in a Fourier transform ion cyclotron resonance mass spectrometer using a consecutive exchange reaction of the xenon dimer radical cation with methyl chloride. Both theory and experiment have indicated the existence of two different stable methyl chloride dimer radical cations, that is a two-center three-electron (2c/3e) bonded dimer radical cation, CH3Cl∴ClCH3•+, with C2 symmetry and a methyl chloride chloronium ylidion structure, CH3Cl·H·ClCH2•+, with Cs symmetry. The CH3Cl∴ClCH3•+ species has been observed to react both as an electron acceptor and as a proton donor. The CH3Cl·H·ClCH2•+ structure, however, reacts only as an electron acceptor. Calculations of the CH3Cl∴ClCH3•+ structure at the MP2/6-311G(d,p) level of theory indicate a bond dissociation energy of 105.4 kJ mol-1 relative to its ionized and neutral monomer products, while experiments show a bond dissociation energy of 109 ± 5 kJ mol-1. The bond dissociation energy of the CH3Cl·H·Cl...

The reactions of the atomic oxygen radical anion O −• with CH 3 S CH 2 CN in the gas phase have been examined with Fourier transform ion cyclotron resonance in combination with tandem mass spectrometric experiments performed with a double-focusing quadrupole hybrid instrument. Deuterium labeling has revealed that the O −• ion reacts with CH 3 S CH 2 CN by proton abstraction from the methylene group as well as by competing 1,1- and 1,3-H 2 +• abstractions to afford isomeric radical anions. High kinetic energy (8 keV) collision-induced charge reversal experiments indicate that the 1,1-H 2 +• -abstraction leads to a CH 3 S C CN carbene ion, whereas the 1,3-H 2 +• abstraction yields a novel sulfur-containing distonic radical anion, which is formulated as CH 2 S CH CN.

The gas-phase reactivity of CH 3 NHOCH 3 (N,O-dimethylhydrorylamine, DHA) and NH 2 OCH 3 (O-methylhydrorylamine, MHA) toward a series of anionic bases has been studied using the method of Fourier transform ion cyclotron resonance (FT-ICR) miass spectrometry. Both DHA and MHA undergo a competing proton attraction from and nucleophilic substitution reaction on the nitrogen atom. The competition between these processes is governed by the strength of the base used. Unexpectedly, the nucleophilic attack on the nitrogen atom leading to the substitution of the methoxy group is found to be a relatively facile process

The gas-phase reactions between a series of monohydrated enolate anions and unsaturated perfluorocarbon compounds have been studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The influence of selective solvation at the oxygen atom on the ambident reactivity of enolate anions in the gas phase is investigated through comparison of the observed product distributions with previously obtained data for the corresponding unsolvated anions

The strength of the CN/CN' bond decreases in the series NC-CN (1), CN-CN (2), and CN-NC (3), while simultaneously it shortens. The explanation requires that, apart from the σ pair bond between the CN 5σ MO's, the following effects be taken into account: (a) Pauli repulsion («steric hindrance») between the 4σ («N lone pair») orbitals; (b) Pauli repulsion between the 4σ and 5σ orbitals; (c) donor/acceptor interaction between the 4σ and 5σ orbitals; (d) donor/acceptor interaction between the occupied 1 π and unoccupied 2π *

It is shown by mass-analyzed ion kinetic energy spectrometry that the metastably decomposing molecular ions of octopamine (p-HOC6H4CH(OH)CH2NH2) and synephrine (p-HOC6H4CH(OH)CH2NHCH3) yield only protonated methylamine and dimethylamine, respectively, as product ions. From deuterium labeling and variation of the internal energy of the molecular ions, experimental support has been obtained that these product ions are generated via the occurrence of a distonic ion-neutral complex. In the case of octopamine, this complex would consist of a nitrogen-protonated aminomethyl radical and p-hydroxylbenzaldehyde in which the former species abstracts the aldehydic or phenolic hydrogen atom from the latter to give protonated dimethylamine.

Les reactions de deplacement d'alcoolate exothermiques d'alcanol-alcoolates avec des ethers du bore, du carbone, du silicium et du titane sont controlees essentiellement par les effets specifiques d'orientation lors de l'approche des deux reactifs et non seulement par les barrieres internes

Etude de l'enlevement de proton a partir du formiate de methyle et du DMF en phase gazeuse par spectrometrie de masse FT-ICR

L'importance relative des diverses voies reactionnelles, l'enlevement d'un proton formyl ou methyl, l'addition de carbonyle ou le deplacement sur le groupe methyl, est mesuree

Les ions moleculaires des isomeres endo, mais pas exo, des composes du titre eliminent C 3 H 6 via une reaction retro-Diels Alda. Cette fragmentation fortement stereospecifique necessite un double transfert d'hydrogene dans les ions moleculaires qui a lieu de maniere concertee

On montre qu'il est possible de generer l'ion H 2 O ― • dans un spectrometre FTICR par reaction de O ― • avec une amine aliphatique. L'espece H 2 O ― • reagit rapidement avec le formaldehyde pour donner OH − . A temperature ambiante on peut obtenir un rendement optimum de H 2 O ― •