Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

McAskill, NA

doi:10.1071/ch9700893

Cited by 15 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The profile of the product ion signal variation as a function of neutral reagent for each individual reaction indicates which secondary processes are occurring at higher neutral gas flow. The vast majority of these graphs for CHCl 2 F and CHClF 2 mimic those obtained using a high-pressure mass spectrometer, in that CHClF + reacts on to form CHCl 2 + in the former case and CHF 2 + produces CHClF + at high flows of the neutral reactant. The only exceptions to this consensus are those plots derived from reactions involving ions with high recombination energies, where the presence of more fragmented products complicates this matter.…”

Section: Discussionmentioning

confidence: 59%

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

2005

View full text Add to dashboard Cite

rate, but the reagent ions SF 3 + , NO + , NO 2 + and SF 2 + do not react. Surprisingly, although all of the observed product channels are calculated to be endothermic, H 3 O + does react with CHCl 2 F. On thermochemical grounds, Xe + appears to react with these molecules only when it is in its higher-energy 2 P 1/2 spin-orbit state. In general, most of the reactions form products by dissociative charge transfer, but some of the reactions of CH 2 ClF with the lower-energy cations produce the parent cation in significant abundance. The branching ratios produced in this study and by threshold photoelectron-photoion coincidence spectroscopy (preceding paper) agree reasonably well over the energy range 11 − 22 eV. In about one fifth of the large number of reactions studied the branching ratios are in excellent agreement and appreciable energy resonance between an excited state and the ground state of the ionized neutral exists, suggesting that these reactions proceed exclusively by a long-range charge transfer mechanism.Upper limits for the enthalpy of formation at 298 K of SF 4 Cl (−637 kJ mol -1 ), SClF (−28 kJ mol -1 ) and SHF (−7 kJ mol -1 ) are determined. 3 IntroductionThe study of ion-molecule reactions is of importance in many areas of science, such as plasmas found in industrial applications and in the interstellar medium. 1,2 These fundamental processes underpin the complex reactivity that is evident in these systems. One such mechanism is that of charge transfer, which can occur over either a long-range or a short-range. The former model states that as an ion (A + ) makes an approach toward a neutral reagent (BC), the ionic charge induces a dipole interaction in the neutral. At a critical separation between the two species, the potential curves of A + −BC and A−BC + cross, thus allowing an electron to jump from the neutral to the ion. Factors that exhibit a marked preference for the occurrence of this process include energy resonance between the ground electronic state and an ionic state of the neutral and the extent of shielding in the molecular orbital from which the electron is removed. A guide to the possible energy resonances can be found in the photoelectron spectrum (PES) of the neutral species. For the molecular reagent cations, the Franck-Condon factor for neutralising A + can also be important. If the long-range process is unfavourable, then the two species move closer together. The resulting intimate interaction can perturb the relevant potential surfaces to such an extent that a crossing is stimulated, thereby leading to short-range charge transfer. Note that, in this case, although the FranckCondon factors involved are perturbed, they still need to be appreciable in the isolated molecule for this process to transpire. Short-range charge transfer can compete with chemical reactions, where bonds are broken and formed. As neither a curve crossing nor a Franck-Condon factor is required for a chemical reaction to occur, this channel can proceed efficiently. A thorough review of the aforementioned ...

show abstract

Section: Discussionmentioning

confidence: 59%

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

2005

View full text Add to dashboard Cite

show abstract

“…Halide-abstraction is a familiar gas-phase reaction between carbocations and alkyl halides. 28,29 The reaction proceeds by the facile formation of a dialkylhalonium ion intermediate (Fig. 1).…”

Section: ؒ and X ؊ Abstractionmentioning

confidence: 99%

Gas-phase reactions of the dichlorocarbene radical cation

Nelson¹,

Tichy²,

Kenttämaa³

1999

J. Chem. Soc., Perkin Trans. 2

View full text Add to dashboard Cite

“…CCl + itself has yet to be detected, although it is expected to be present and is usually included in theoretical models of ISM chemistry. − While CCl + has a demonstrated formation reaction from C + + HCl, CCl + itself has only been reacted with a limited scope of astrochemically relevant molecules. A series of experiments demonstrated the reactivity of CCl + with NH 3 , H 2 CO, CH 3 Cl, CHCl 3 , CCl 4 , CHCl 2 F, and CHClF 2 , ,− the first three of which are demonstrated to be in the ISM. However, CCl + was shown to be unreactive with NO, H 2 , CH 4 , N 2 , O 2 , CO, CO 2 , HCN. ,, In the 30 years since these experiments, CCl + has been effectively overlooked in laboratory ion-neutral molecular reaction studies despite several gaps in our knowledge of its reactivity.…”

Section: Radiofrequency Trapping and Chemistry With Ccl+mentioning

confidence: 99%

Cold Ion–Molecule Reactions in the Extreme Environment of a Coulomb Crystal

Krohn,

Lewandowski

2024

J. Phys. Chem. A

View full text Add to dashboard Cite

Coulomb crystals provide a unique environment in which to study ion-neutral gas-phase reactions. In these cold, trapped ensembles, we are able to study the kinetics and dynamics of small molecular systems. These measurements have connections to chemistry in the Interstellar Medium (ISM) and planetary atmospheres. This Feature Article will describe recent work in our laboratory that uses Coulomb crystals to study translationally cold, ion-neutral reactions. We provide a description of how the various affordances of our experimental system allow for detailed studies of the reaction mechanisms and the corresponding products. In particular, we will describe quantum-state resolved reactions, isomer-dependent reactions, and reactions with a rarely studied, astrophysically relevant ion, CCl + .

show abstract

Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

Cited by 15 publications

References 0 publications

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

Gas-phase reactions of the dichlorocarbene radical cation

Cold Ion–Molecule Reactions in the Extreme Environment of a Coulomb Crystal

Contact Info

Product

Resources

About

Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

Cited by 15 publications

References 0 publications

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl2F, CHClF2, and CH2ClF

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl2F, CHClF2, and CH2ClF

Gas-phase reactions of the dichlorocarbene radical cation

Cold Ion–Molecule Reactions in the Extreme Environment of a Coulomb Crystal

Contact Info

Product

Resources

About

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF

Selected Ion Flow Tube Study of the Reactions between Gas Phase Cations and CHCl₂F, CHClF₂, and CH₂ClF