<b>Free Radicals by Mass Spectrometry. XXIX. Ionization Potentials of Substituted Cyclopentadienyl Radicals</b>

Pottie, R. F.; Lossing, F. P.

doi:10.1021/ja00886a004

Cited by 38 publications

(22 citation statements)

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“…1 using more reliable ionization energies from the tabulation of Lias et al 17 Some limited correlations of the ionization energies of disubstituted benzenes with C para also have been reported. 18 In 1961, Harrison et al 19 reported that the ionization energies of meta-and para-substituted benzyl radicals correlated more closely, as expected, with Brown while Pottie and Lossing 21 reported that the ionization energies of substituted cyclopentadienyl radicals showed a reasonable correlation with C para for the substituent. Grubb and Meyerson, 22 from a study of the fragmentation of 13 C-and 2 H-labelled C 7 H 7 C ions derived from benzyl derivatives, concluded that the fragmenting ions had the symmetrical tropylium structure rather than the benzyl structure.…”

Section: Ionization and Appearance Energiesmentioning

confidence: 75%

Linear free energy correlations in mass spectrometry

Harrison

1999

J. Mass Spectrom.

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Section: Ionization and Appearance Energiesmentioning

confidence: 75%

Linear free energy correlations in mass spectrometry

Harrison

1999

J. Mass Spectrom.

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“…For estimation of the heat of formation for the 1hydroxycyclopentadienyl ion Ig we should know the value for an analogue substituted at position 1. Unfortunately, existing IE data for 1-R-cyclopentadienyl free radicals were obtained using a rather inaccurate EI method, 13 and cannot be used to obtain correct thermochemical data for 1-R cyclopentadienyl ions. Our attempt to obtain the value of the heat of formation for a substituted cyclopentadienyl cation-the indenyl ion from methylindene-was not successful (see Appendix).…”

Section: -Methyl-3-acetylcyclopropene (I) [M -Me] + Ionmentioning

confidence: 99%

Thermochemistry of organic and heteroorganic species. Part V. Photoionization studies of isomerization and fragmentation of polysubstituted cyclopropenes: 3-methyl-3-acetyl- and related compounds

Domnin

Takhistov

Ponomarev

1999

Eur. J. Mass Spectrom.

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Appearance energies for molecular and some fragment ions from 3-methyl-3-acetyl-, 1,2-dimethyl-3-acetyl-, 1,2-dimethyl-3hydroxycarbonyl-and 1,3-dimethyl-2-(1-methyl)vinylcyclopropenes and model compounds 2,3-dimethylfuran and 1-methylindene were measured by photoionization mass spectrometry. It was shown that, in all cases, the structure of the [M-Me] + ion does not correspond to the expected structures of substituted cyclopropenium ions. Possible schemes for formation of [M-Me] + ions are given. Isodesmic reactions were systematically applied for calculation of the heats of formation for 35 possible C 5 H 5 O + isomers from 3methyl-3-acetyl-cyclopropene. In addition, the heats of formation for more than 30 other unsaturated ions and free radicals were estimated with the help of series of isodesmic reactions. A new value of 160 kJ mol-1 , as compared with the currently used value of 215.5 kJ mol-1 , for the cyclopropylmethyl free radical is suggested. The publication represents the further development of the methodology for the heat of formation estimation procedure for even-electron ions and free radicals.

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“…[17] Spectroscopic investigations of indenyl radicals are even sparser. Using electron impact ionization, Pottie and Lossing [18] deduced an adiabatic ionization energy (AIE) of the 1H-inden-1yl as 8.35 eV while a vacuum ultraviolet (VUV) photoionization study by Fischer et al [19] determined the AIE to be 7.53 eV and identified an excited 3 B 2 state of the cation at 8.10 eV. Another VUV study reports the AIE of 7.48 eV [20] and an estimate for the enthalpy of formation of the neutral radical Δ f H°0 K of 249 � 50 kJ mol À 1 .…”

Section: Introductionmentioning

confidence: 99%

Reactivity of the Indenyl Radical (C₉H₇) with Acetylene (C₂H₂) and Vinylacetylene (C₄H₄)

et al. 2019

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The reactions of the indenyl radicals with acetylene (C2H2) and vinylacetylene (C4H4) is studied in a hot chemical reactor coupled to synchrotron based vacuum ultraviolet ionization mass spectrometry. These experimental results are combined with theory to reveal that the resonantly stabilized and thermodynamically most stable 1‐indenyl radical (C9H7.) is always formed in the pyrolysis of 1‐, 2‐, 6‐, and 7‐bromoindenes at 1500 K. The 1‐indenyl radical reacts with acetylene yielding 1‐ethynylindene plus atomic hydrogen, rather than adding a second acetylene molecule and leading to ring closure and formation of fluorene as observed in other reaction mechanisms such as the hydrogen abstraction acetylene addition or hydrogen abstraction vinylacetylene addition pathways. While this reaction mechanism is analogous to the bimolecular reaction between the phenyl radical (C6H5.) and acetylene forming phenylacetylene (C6H5CCH), the 1‐indenyl+acetylene→1‐ethynylindene+hydrogen reaction is highly endoergic (114 kJ mol−1) and slow, contrary to the exoergic (−38 kJ mol−1) and faster phenyl+acetylene→phenylacetylene+hydrogen reaction. In a similar manner, no ring closure leading to fluorene formation was observed in the reaction of 1‐indenyl radical with vinylacetylene. These experimental results are explained through rate constant calculations based on theoretically derived potential energy surfaces.

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Free Radicals by Mass Spectrometry. XXIX. Ionization Potentials of Substituted Cyclopentadienyl Radicals

Cited by 38 publications

References 0 publications

Linear free energy correlations in mass spectrometry

Linear free energy correlations in mass spectrometry

Thermochemistry of organic and heteroorganic species. Part V. Photoionization studies of isomerization and fragmentation of polysubstituted cyclopropenes: 3-methyl-3-acetyl- and related compounds

Reactivity of the Indenyl Radical (C₉H₇) with Acetylene (C₂H₂) and Vinylacetylene (C₄H₄)

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Free Radicals by Mass Spectrometry. XXIX. Ionization Potentials of Substituted Cyclopentadienyl Radicals

Cited by 38 publications

References 0 publications

Linear free energy correlations in mass spectrometry

Linear free energy correlations in mass spectrometry

Thermochemistry of organic and heteroorganic species. Part V. Photoionization studies of isomerization and fragmentation of polysubstituted cyclopropenes: 3-methyl-3-acetyl- and related compounds

Reactivity of the Indenyl Radical (C9H7) with Acetylene (C2H2) and Vinylacetylene (C4H4)

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Reactivity of the Indenyl Radical (C₉H₇) with Acetylene (C₂H₂) and Vinylacetylene (C₄H₄)