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Does addition of NO2 to carbon-centered radicals yield RONO or RNO2? An investigation using distonic radical ions

Journal Article


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Abstract


  • Nitrogen dioxide is used as a "radical scavenger" to probe the position of carbon-centered radicals within complex radical ions in the gas phase. As with analogous neutral radical reactions, this addition results in formation of an [M + NO2](+) adduct, but the structural identity of this species remains ambiguous. Specifically, the question remains: do such adducts have a nitro-(RNO2) or nitrosoxy-(RONO) moiety, or are both isomers present in the adduct population? In order to elucidate the products of such reactions, we have prepared and isolated three distonic phenyl radical cations and observed their reactions with nitrogen dioxide in the gas phase by ion-trap mass spectrometry. In each case, stabilized [M + NO2](+) adduct ions are observed and isolated. The structure of these adducts is probed by collision-induced dissociation and ultraviolet photodissociation action spectroscopy and a comparison made to the analogous spectra of authentic nitro-and nitrosoxy-benzenes. We demonstrate unequivocally that for the phenyl radical cations studied here, all stabilized [M + NO2](+) adducts are exclusively nitrobenzenes. Electronic structure calculations support these mass spectrometric observations and suggest that, under low-pressure conditions, the nitrosoxy-isomer is unlikely to be isolated from the reaction of an alkyl or aryl radical with NO2. The combined experimental and theoretical results lead to the prediction that stabilization of the nitrosoxy-isomer will only be possible for systems wherein the energy required for dissociation of the RO-NO bond (or other low energy fragmentation channels) rises close to, or above, the energy of the separated reactants.

Authors


  •   Kirk, Benjamin B. (external author)
  •   Trevitt, Adam J.
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2013

Citation


  • Kirk, B. B., Trevitt, A. J. & Blanksby, S. J. (2013). Does addition of NO2 to carbon-centered radicals yield RONO or RNO2? An investigation using distonic radical ions. Journal of the American Society for Mass Spectrometry, 24 (4), 481-492.

Scopus Eid


  • 2-s2.0-84879525158

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1628&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/615

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 481

End Page


  • 492

Volume


  • 24

Issue


  • 4

Place Of Publication


  • United States

Abstract


  • Nitrogen dioxide is used as a "radical scavenger" to probe the position of carbon-centered radicals within complex radical ions in the gas phase. As with analogous neutral radical reactions, this addition results in formation of an [M + NO2](+) adduct, but the structural identity of this species remains ambiguous. Specifically, the question remains: do such adducts have a nitro-(RNO2) or nitrosoxy-(RONO) moiety, or are both isomers present in the adduct population? In order to elucidate the products of such reactions, we have prepared and isolated three distonic phenyl radical cations and observed their reactions with nitrogen dioxide in the gas phase by ion-trap mass spectrometry. In each case, stabilized [M + NO2](+) adduct ions are observed and isolated. The structure of these adducts is probed by collision-induced dissociation and ultraviolet photodissociation action spectroscopy and a comparison made to the analogous spectra of authentic nitro-and nitrosoxy-benzenes. We demonstrate unequivocally that for the phenyl radical cations studied here, all stabilized [M + NO2](+) adducts are exclusively nitrobenzenes. Electronic structure calculations support these mass spectrometric observations and suggest that, under low-pressure conditions, the nitrosoxy-isomer is unlikely to be isolated from the reaction of an alkyl or aryl radical with NO2. The combined experimental and theoretical results lead to the prediction that stabilization of the nitrosoxy-isomer will only be possible for systems wherein the energy required for dissociation of the RO-NO bond (or other low energy fragmentation channels) rises close to, or above, the energy of the separated reactants.

Authors


  •   Kirk, Benjamin B. (external author)
  •   Trevitt, Adam J.
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2013

Citation


  • Kirk, B. B., Trevitt, A. J. & Blanksby, S. J. (2013). Does addition of NO2 to carbon-centered radicals yield RONO or RNO2? An investigation using distonic radical ions. Journal of the American Society for Mass Spectrometry, 24 (4), 481-492.

Scopus Eid


  • 2-s2.0-84879525158

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1628&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/615

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 481

End Page


  • 492

Volume


  • 24

Issue


  • 4

Place Of Publication


  • United States