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J Am Soc Mass Spectrom

Title:		Comparing Positively and Negatively Charged Distonic Radical Ions in Phenylperoxyl Forming Reactions
Author(s):		Williams PE; Marshall DL; Poad BLJ; Narreddula VR; Kirk BB; Trevitt AJ; Blanksby SJ;
Address:		"Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, Australia. Failure and Materials Analysis Branch, Flight Systems Division, Naval Surface Warfare Center Crane, Crane, IN, USA. School of Chemistry, University of Wollongong, Wollongong, NSW, Australia. Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, Australia. stephen.blanksby@qut.edu.au"
Journal Title:		J Am Soc Mass Spectrom
Year:		2018
Volume:		20180604
Issue:		9
Page Number:		1848 - 1860
DOI:		10.1007/s13361-018-1988-9
ISSN/ISBN:		1879-1123 (Electronic) 1044-0305 (Linking)
Abstract:		"In the gas phase, arylperoxyl forming reactions play a significant role in low-temperature combustion and atmospheric processing of volatile organic compounds. We have previously demonstrated the application of charge-tagged phenyl radicals to explore the outcomes of these reactions using ion trap mass spectrometry. Here, we present a side-by-side comparison of rates and product distributions from the reaction of positively and negatively charge tagged phenyl radicals with dioxygen. The negatively charged distonic radical ions are found to react with significantly greater efficiency than their positively charged analogues. The product distributions of the anion reactions favor products of phenylperoxyl radical decomposition (e.g., phenoxyl radicals and cyclopentadienone), while the comparable fixed-charge cations yield the stabilized phenylperoxyl radical. Electronic structure calculations rationalize these differences as arising from the influence of the charged moiety on the energetics of rate-determining transition states and reaction intermediates within the phenylperoxyl reaction manifold and predict that this influence could extend to intra-molecular charge-radical separations of up to 14.5 A. Experimental observations of reactions of the novel 4-(1-carboxylatoadamantyl)phenyl radical anion confirm that the influence of the charge on both rate and product distribution can be modulated by increasing the rigidly imposed separation between charge and radical sites. These findings provide a generalizable framework for predicting the influence of charged groups on polarizable radicals in gas phase distonic radical ions. Graphical Abstract"
Keywords:		Distonic ions Electronic structure calculations Ion-molecule reactions Peroxyl radicals Phenyl radicals Reaction kinetics;
Notes:		"PubMed-not-MEDLINEWilliams, Peggy E Marshall, David L Poad, Berwyck L J Narreddula, Venkateswara R Kirk, Benjamin B Trevitt, Adam J Blanksby, Stephen J eng DP140101237/Australian Research Council/International DP170101596/Australian Research Council/International 2018/06/06 J Am Soc Mass Spectrom. 2018 Sep; 29(9):1848-1860. doi: 10.1007/s13361-018-1988-9. Epub 2018 Jun 4"