Dioxygen: What Makes This Triplet Diradical Kinetically Persistent?

Weston Thatcher Borden, Roald Hoffmann, Thijs Stuyver, Bo Chen

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

Experimental heats of formation and enthalpies obtained from G4 calculations both find that the resonance stabilization of the two unpaired electrons in triplet O2, relative to the unpaired electrons in two hydroxyl radicals, amounts to 100 kcal/mol. The origin of this huge stabilization energy is described within the contexts of both molecular orbital (MO) and valence-bond (VB) theory. Although O2 is a triplet diradical, the thermodynamic unfavorability of both its hydrogen atom abstraction and oligomerization reactions can be attributed to its very large resonance stabilization energy. The unreactivity of O2 toward both these modes of self-destruction maintains its abundance in the ecosphere and thus its availability to support aerobic life. However, despite the resonance stabilization of the ? system of triplet O2, the weakness of the O-O σ bond makes reactions of O2, which eventually lead to cleavage of this bond, very favorable thermodynamically.

Original languageEnglish (US)
Pages (from-to)9010-9018
Number of pages9
JournalJournal of the American Chemical Society
Volume139
Issue number26
DOIs
StatePublished - Jul 5 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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