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Experimental evidence for long-range stabilizing and destabilizing interactions between charge and radical sites in distonic ions

Journal Article


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Abstract


  • Polarizable radical sites in distonic radical anions are stabilized by ostensibly remote negative charges. Computational evidence suggests bond dissociation energies of closed-shell precursors are significantly lowered by through-space interactions with a proximate negative charge, however direct experimental confirmation has proved challenging. Herein, we exploit two complementary tandem mass spectrometry strategies to probe the influence of a remote charge on the stability of nitroxyl radicals, and vice versa. Dissociation of negatively charge-tagged alkoxyamines reveals that the energetic onset of radical formation is dependent on the proximity and basicity of the charged group, thus providing direct evidence for a charge-induced stabilization of the nitroxyl radical. Complementary kinetic method experiments on a series of proton-bound dimers demonstrate that the presence of a nitroxyl radical decreases the proton affinity for a selection of proximate ionic groups. These data show excellent agreement with quantum-chemical calculations and provide a general framework to explore the magnitude and direction of charge-radical interactions through systematic exploration of the identity, polarity and the proximity of the ion to the radical site. These findings expand our fundamental understanding of radical ion energetics that underpin the application of distonic ions as models for neutral radical reactivity, and open new avenues for exploiting these interactions as chemical switches.

Authors


  •   Marshall, David L. (external author)
  •   Gryn'ova, Ganna (external author)
  •   Poad, Berwyck L. J. (external author)
  •   Bottle, Steven (external author)
  •   Trevitt, Adam J.
  •   Coote, M L. (external author)
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2019

Citation


  • Marshall, D. L., Gryn'ova, G., Poad, B. L. J., Bottle, S. E., Trevitt, A. J., Coote, M. & Blanksby, S. J. (2019). Experimental evidence for long-range stabilizing and destabilizing interactions between charge and radical sites in distonic ions. International Journal of Mass Spectrometry, 435 195-203.

Scopus Eid


  • 2-s2.0-85056212966

Ro Full-text Url


  • https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1446&context=smhpapers1

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/434

Number Of Pages


  • 8

Start Page


  • 195

End Page


  • 203

Volume


  • 435

Place Of Publication


  • Netherlands

Abstract


  • Polarizable radical sites in distonic radical anions are stabilized by ostensibly remote negative charges. Computational evidence suggests bond dissociation energies of closed-shell precursors are significantly lowered by through-space interactions with a proximate negative charge, however direct experimental confirmation has proved challenging. Herein, we exploit two complementary tandem mass spectrometry strategies to probe the influence of a remote charge on the stability of nitroxyl radicals, and vice versa. Dissociation of negatively charge-tagged alkoxyamines reveals that the energetic onset of radical formation is dependent on the proximity and basicity of the charged group, thus providing direct evidence for a charge-induced stabilization of the nitroxyl radical. Complementary kinetic method experiments on a series of proton-bound dimers demonstrate that the presence of a nitroxyl radical decreases the proton affinity for a selection of proximate ionic groups. These data show excellent agreement with quantum-chemical calculations and provide a general framework to explore the magnitude and direction of charge-radical interactions through systematic exploration of the identity, polarity and the proximity of the ion to the radical site. These findings expand our fundamental understanding of radical ion energetics that underpin the application of distonic ions as models for neutral radical reactivity, and open new avenues for exploiting these interactions as chemical switches.

Authors


  •   Marshall, David L. (external author)
  •   Gryn'ova, Ganna (external author)
  •   Poad, Berwyck L. J. (external author)
  •   Bottle, Steven (external author)
  •   Trevitt, Adam J.
  •   Coote, M L. (external author)
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2019

Citation


  • Marshall, D. L., Gryn'ova, G., Poad, B. L. J., Bottle, S. E., Trevitt, A. J., Coote, M. & Blanksby, S. J. (2019). Experimental evidence for long-range stabilizing and destabilizing interactions between charge and radical sites in distonic ions. International Journal of Mass Spectrometry, 435 195-203.

Scopus Eid


  • 2-s2.0-85056212966

Ro Full-text Url


  • https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1446&context=smhpapers1

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/434

Number Of Pages


  • 8

Start Page


  • 195

End Page


  • 203

Volume


  • 435

Place Of Publication


  • Netherlands