Structural fluxionality in the tricyclo[]nona-3,6-dienyl and bicyclo[3.2.2]nona-2,6,8-trienyl radicals

John C. Walton*

*Corresponding author for this work

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5 Citations (Scopus)


E.s.r. observation of radicals derived from 9-bromotricyclo[]nona-3,6-diene, and related compounds, showed that they rearrange by β-scission to bicyclo[3.2.2]nona-2,6,8-trienyl radicals extremely rapidly; the latter radicals have hyperfine splittings similar to those of allyl radicals. 9-Deuterio- and 2-deuterio-9-bromotricyclo []nona-3,6-diene were reduced with tributyltin hydride. The pattern of deuterium scrambling in the bicyclo[3.2.2]nona-2,6,8-triene and tricyclo[]nona-3,6-diene products showed that the intermediate radicals take part in a degenerate rearrangement sequence which makes them fully fluxional in three dimensions. The two radicals are in equilibrium at ca. 375 K, but the bicyclotrienyl species is more important by a factor of ca. 102. Neither the experimental results nor MNDO semiempirical calculations provided any evidence of additional thermodynamic stabilisation in the radical pair beyond that expected for allyl delocalisation.

Original languageEnglish
Pages (from-to)2169-2176
Number of pages8
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number12
Publication statusPublished - 1 Jan 1989


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