Oxygenation of the phenylhalocarbenes: Are they spin-allowed or spin-forbidden reactions?
2012 (English)In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 18, no 6, 2813-2821 p.Article in journal (Refereed) Published
Oxygenation mechanisms of phenylhalocarbenes in vacuum are investigated through the use of density functional theory and CASSCF-PT2 approaches. Reactions with both substituted and unsubstituted phenylhalocarbenes are strongly exothermic. The reactions with nitrosubstituted halocarbenes are predicted to be spin allowed due to the practical degeneracy of the singlet and triplet carbene states. Conversely, for the unsubstituted compounds, the equilibrium between the triplet carbene and O-3(2) requires a previous singlet-triplet state crossing. The large spin-orbit coupling at this crossing suggests a rather efficient tunneling rate. This would help to explain why the rate constant in solution in these cases is only one order of magnitude smaller than those involving a spin-allowed process. Moreover, the action of the solvent as a third body appears to play a fundamental role in prompting relatively smooth rates.
Place, publisher, year, edition, pages
2012. Vol. 18, no 6, 2813-2821 p.
Halocarbene reactivity, DFT, Spin-philicity index, Singlet-triplet reaction, CASSCF-PT2
IdentifiersURN: urn:nbn:se:uu:diva-176815DOI: 10.1007/s00894-011-1283-1ISI: 000304621400051OAI: oai:DiVA.org:uu-176815DiVA: diva2:537726