Long Zhao, Gap-Sue Kim, Ralf I. Kaiser, Michael Lucas, Aaron M. Thomas, Alexander M. Mebel
The 1,2,4,7-cyclooctatetraenyl radical (C8H7) has been synthesized for the very first time via the bimolecular gas-phase reaction of ground-state carbon atoms with 1,3,5-cycloheptatriene (C7H8) on the triplet surface under single-collision conditions. The barrier-less route to the cyclic 1,2,4,7-cyclooctatetraenyl radical accesses exotic reaction intermediates on the triplet surface, which cannot be synthesized via classical organic chemistry methods: the triplet non-aromatic 2,4,6-cyclooctatriene (C8H8) and the triplet aromatic 1,3,5,7-cyclooctatetraene (C8H8). Our approach provides a clean gas-phase synthesis of this hitherto elusive cyclic radical species 1,2,4,7-cyclooctatetraenyl via a single-collision event and opens up a versatile, unconventional path to access this previously largely obscure class of cyclooctatetraenyl radicals, which have been impossible to access through classical synthetic methods.
Carbon eight-ed: Gas-phase reaction of ground-state carbon atoms and cycloheptatriene (C7H8) under single-collision conditions leads to the production of the 1,2,4,7-cyclooctatetraenyl radical (C8H7). Ab initio electronic structure calculation shows the reaction proceeds via exotic triplet C8H8 reaction intermediates: the non-aromatic 2,4,6-cyclooctatriene and the aromatic 1,3,5,7-cyclooctatetraene. The picture shows the flux contour map of the reaction.