title: Roaming dynamics in radical addition-elimination reactions.
abstract: Radical addition-elimination reactions are a major pathway for transformation of unsaturated hydrocarbons. In the gas phase, these reactions involve formation of a transient strongly bound intermediate. However, the detailed mechanism and dynamics for these reactions remain unclear. Here we show, for reaction of chlorine atoms with butenes, that the Cl addition-HCl elimination pathway occurs from an abstraction-like Cl-H-C geometry rather than a conventional three-centre or four-centre transition state. Furthermore, access to this geometry is attained by roaming excursions of the Cl atom from the initially formed adduct. In effect, the alkene π cloud serves to capture the Cl atom and hold it, allowing many subsequent opportunities for the energized intermediate to find a suitable approach to the abstraction geometry. These bimolecular roaming reactions are closely related to the roaming radical dynamics recently discovered to play an important role in unimolecular reactions.
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Joalland
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kamasah
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
authors.forename: Arthur G
authors.initials: AG
authors.lastname: Suits
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Mebel