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Journal ArticleDOI

Recent advances in the energetics and mechanisms of gas-phase ionic reactions

30 Jan 1998-Pure and Applied Chemistry (International Union of Pure and Applied Chemistry)-Vol. 70, Iss: 10, pp 1969-1976
TL;DR: In this article, the authors review some recent results of our laboratories: 1) the use of incoherent infrared radiation to promote multiphoton dissociation of ions is shown to be an efficient and convenient method to determine the energetics of ions and provide structural information of ions.
Abstract: Three important aspects are still at the forefront of gas-phase ion chemistry: structure and energetics, mechanisms of gas-phase reactions relevant to condensed phases, and bridging the gap between gas-phase and solution. In this paper, we review some recent results of our laboratories: 1) The use of incoherent infrared radiation to promote multiphoton dissociation of ions is shown to be an efficient and convenient method to determine the energetics of ions and provide structural information of ions. 2) New experimental and theoretical data provide some interesting comparison between nucleophilic reactions at carbon, silicon and germanium centers. In the latter cases, the mechanism involves primarily an attachment-detachment process. 3) The ability to make gas-phase anions attached to neutral molecules provides an interesting approach towards the study of the stability, reactivity, structure and spectroscopy of gas-phase solvated ions.

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TL;DR: In this article, the thermal dissociation of substituted acetophenone molecular ions induced by infrared radiation from a hot wire has been studied in a Fourier transform ion cyclotron resonance spectrometer.
Abstract: The thermal dissociation of several substituted acetophenone molecular ions induced by infrared radiation from a hot wire has been studied in a Fourier transform ion cyclotron resonance spectrometer. The temperature dependence of the dissociation rate constants reveals that the 2'-methylacetophenone molecular ion is characterized by a much higher activation energy for dissociation than other acetophenones. This molecular ion also exhibits a very different behavior with respect to charge-transfer reactions. Unlike molecular ions obtained from other isomeric acetophenones, the 2'-methylacetophenone M + ° ion does not promote charge exchange with dimethyl disulfide but does undergo relatively slow electron transfer with ferrocene (IE = 6.74 eV). Ab initio calculations at the MP2/6-31G(d) level predict that the 2-MeC 6 H 4 COCH 3 +° ion (1) can undergo facile tautomerization to the much more stable enol ion 2, 2'-CH 2 C 6 H 4 C + (OH)CH 3 , by a 1,4-hydrogen migration (calculated energy barrier of 20 kJ mol - 1 ). The calculated recombination energy of this ion is in good agreement with the observations from the charge-exchange experiments. A full analysis of the potential energy surface suggests that, at low ionizing energies (≤11.5 eV), essentially all of the long-lived molecular ions have isomerized to 2. The present example reveals the versatility and some of the advantages of the high-temperature near-blackbody-induced dissociation (hot wire emission) for probing structural problems in ion chemistry.

10 citations

Journal ArticleDOI
TL;DR: In this article, the authors review some recent results of our laboratories: 1) the use of incoherent infrared radiation to promote multiphoton dissociation of ions is shown to be an efficient and convenient method to determine the energetics of ions and provide structural information of ions.
Abstract: Three important aspects are still at the forefront of gas-phase ion chemistry: structure and energetics, mechanisms of gas-phase reactions relevant to condensed phases, and bridging the gap between gas-phase and solution. In this paper, we review some recent results of our laboratories: 1) The use of incoherent infrared radiation to promote multiphoton dissociation of ions is shown to be an efficient and convenient method to determine the energetics of ions and provide structural information of ions. 2) New experimental and theoretical data provide some interesting comparison between nucleophilic reactions at carbon, silicon and germanium centers. In the latter cases, the mechanism involves primarily an attachment-detachment process. 3) The ability to make gas-phase anions attached to neutral molecules provides an interesting approach towards the study of the stability, reactivity, structure and spectroscopy of gas-phase solvated ions.
References
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Book
01 Jan 1988
TL;DR: Ion cyclotron resonance spectrometry Fourier transform mass spectrometer neutral products from electron bombardment flow studies flowing afterglow and sift pulsed electron high pressure mass spectrumeter nuclear decay techniques ion beam methods state-selected and state-to-state ion-molecules reaction dynamics by photo-ionization methods spectroscopic probes infrared laser photolysis pulsed methods for cluster ion spectroscopy.
Abstract: Ion cyclotron resonance spectrometry Fourier transform mass spectrometry neutral products from electron bombardment flow studies flowing afterglow and sift pulsed electron high pressure mass spectrometer nuclear decay techniques ion beam methods state-selected and state-to-state ion-molecules reaction dynamics by photo-ionization methods spectroscopic probes infrared laser photolysis pulsed methods for cluster ion spectroscopy.

282 citations