Spin-Forbidden Channels in Reactions of Unsaturated Hydrocarbons with O(3P)

Pavel Pokhilko, Robin Shannon, David Glowacki, Hai Wang, Anna I. Krylov*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

21 Citations (Scopus)
439 Downloads (Pure)


The electronic structure of four prototypical Cvetanović diradicals, species derived by addition of O( 3 P) to unsaturated compounds, is investigated by high-level electronic structure calculations and kinetics modeling. The main focus of this study is on the electronic factors controlling the rate of intersystem crossing (ISC): minimal energy crossing points (MECPs) and spin-orbit couplings (SOCs). The calculations illuminate significant differences in the electronic structure of ethene- and ethyne-derived compounds and explain the effect of methylation. The computed MECP heights and SOCs reveal different mechanisms of ISC in ethene- and ethyne-derived species, thus explaining variations in the observed branching ratios between singlet and triplet products and a puzzling effect of methyl substitution. In the ethene- and propene-derived species, the MECP is very low and the rate is controlled by variations of SOC, whereas in the ethyne- and propyne-derived species the MECP is high and the changes in the ISC rate due to methyl substitutions are driven by the variations of MECP heights.

Original languageEnglish
Pages (from-to)482-491
Number of pages10
JournalJournal of Physical Chemistry A
Issue number2
Early online date20 Dec 2018
Publication statusPublished - 17 Jan 2019


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