IR Spectrum of the Ethyl Cation: Evidence for the Nonclassical Structure

Andrei, Horia-Sorin; Solcà, Nicola; Dopfer, Otto

doi:10.1002/ange.200704163

Cited by 23 publications

(11 citation statements)

References 43 publications

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“…If DR processes are completely quenched in the matrix, species such as C 2 D 5 • will be formed in the matrix with a structure that corresponds to that of the gas‐phase C 2 D 5 + at the time of neutralization. In the case of C 2 D 5 + , the only stable structure is the nonclassical C 2 v structure with the proton symmetrically disposed above the double bond . Neutralization of this structure is expected to give rise to matrix‐isolated C 2 D 4 and a D atom.…”

Section: Discussionmentioning

confidence: 51%

Ethane cation decomposition characterization by EBMI spectroscopy: gas‐phase dissociative recombination as a source of secondary products

et al. 2012

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The decomposition products of the d(6) -ethane cation following charge-transfer ionization with Ar(+) , under conditions of varying ionization electron current, have been isolated in solid argon matrices at 18 K and examined using Fourier transform infrared spectroscopy. Gas samples containing 1 : 1600 d(6) -ethane : Ar were subjected to electron bombardment by using either a high (pin) or a low (plate) ionization density anode configuration with ionization currents between 20 and 150 μA. Under high ionization density conditions, the observed major products were d(4) -ethene (C(2) D(4) ) and d(2) -acetylene (C(2) D(2) ), with smaller yields of C(2) D(5) , C(2) D(3) , and C(2) D. The yield of each dehydrogenation product was enhanced with increased current. Analogous experiments employing the low ionization density plate anode resulted in reduced C(2) D(6) destruction and the formation of only C(2) D(4) and C(2) D(2) . The results suggest the onset of dissociative recombination processes under high ion density conditions. In this context, the results can be interpreted as a dissociative recombination of primary ion products, which gives rise to further dehydrogenation, and appearance of additional neutral radical products.

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Section: Discussionmentioning

confidence: 51%

Ethane cation decomposition characterization by EBMI spectroscopy: gas‐phase dissociative recombination as a source of secondary products

et al. 2012

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“…Since in the ethyl cation, such a non-classical bridged geometry is found to be the minimum energy structure, 55 it is reasonable to assume this geometry also for Rydberg-states of the neutral, as confirmed by theory. 25 However, it is difficult to explain the observed siteselectivity in the photodissociation when a bridged isomer is considered, which allows an easy migration of H-atoms.…”

Section: Discussionmentioning

confidence: 67%

The photodissociation dynamics of alkyl radicals

Giegerich

Fischer

2015

The Journal of Chemical Physics

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The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH3)2) and t-butyl (C(CH3)3) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH3CH2, and to those reported for t-butyl using 248 nm excitation. The translational energy (ET) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low ET part of the distribution shows an isotropic photofragment angular distribution, while the high ET part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH3-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

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“…Ethyl cation is predicted by theory to exist exclusively in its bridged proton non‐classical structure (side protonated ethene) the classical form being the transition structure for isomerization via a 1,2‐hydride shift with a critical energy of 30 kJ/mol (Scheme ). Indeed, infrared photodissociation spectroscopy recently provided definite experimental evidence that C 2 H 5 + ion has a non‐classical structure . A high level computational study (CCSD(T)/cc‐pVTZ) reveals that the only stable propyl cation structures are s‐C 3 H 7 + (global minimum of the potential energy surface) and corner protonated cyclopropane (Scheme ).…”

Section: Elementary Reactionsmentioning

confidence: 99%

From the mobile proton to wandering hydride ion: mechanistic aspects of gas‐phase ion chemistry

Bouchoux

2013

J. Mass Spectrom.

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Structural characterization of molecular species by mass spectrometry supposes the knowledge of the type of ions generated and the mechanism by which they dissociate. In this context, a need for a rationalization of electrospray ionization(+)(-) mass spectra of small molecules has been recently expressed. Similarly, at the other end of the mass scale, efforts are currently made to interpret the major fragmentation processes of protonated and deprotonated peptides and their reduced forms produced in electron capture or electron transfer experiments. Most fragmentation processes of molecular and pseudo-molecular ions produced in the ion source of a mass spectrometer may be described by a combination of several key mechanistic steps: simple bond dissociation, formation of ion-neutral complex intermediates, hydrogen atom, hydride ion or proton migrations and nucleophilic attack. Selected crucial aspects of these elementary reactions, occurring inside positively charged ions, will be recalled and illustrated by examples taken in recent mass spectrometry literature. Emphasis will be given on the protonation process and its consequence in terms of structure and energetic.

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IR Spectrum of the Ethyl Cation: Evidence for the Nonclassical Structure

Cited by 23 publications

References 43 publications

Ethane cation decomposition characterization by EBMI spectroscopy: gas‐phase dissociative recombination as a source of secondary products

Ethane cation decomposition characterization by EBMI spectroscopy: gas‐phase dissociative recombination as a source of secondary products

The photodissociation dynamics of alkyl radicals

From the mobile proton to wandering hydride ion: mechanistic aspects of gas‐phase ion chemistry

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