title: 1,4-hydroxybiradical behavior revealed through crystal structure-solid-state reactivity correlations.
abstract: Structure-reactivity correlations for triplet 1,4-hydroxybiradicals in solution are made difficult by the presence of multiple reactive conformers and the possibility of conformation-dependent intersystem crossing. These problems can be overcome by working in the crystalline state, where the conformations of the 1,4-hydroxybiradicals are fixed and determinable by X-ray crystallography of the parent ketones, assuming that hydrogen atom abstraction occurs with little or no change in conformation. This approach is applied to 15 bi- and tricyclic ketones designed to have slightly different biradical conformations, so that the effect of small and incremental changes in geometry on biradical behavior can be tested. The results indicate that, while geometry does have a strong influence on 1,4-hydroxybiradical partitioning between cyclization, cleavage, and reverse hydrogen transfer, a full understanding of the results requires that the strain involved in forming the cyclization products be taken into account.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, Canada V6T 1Z1.
authors.forename: Dario
authors.initials: D
authors.lastname: Braga
authors.forename: Shuang
authors.initials: S
authors.lastname: Chen
authors.forename: Heather
authors.initials: H
authors.lastname: Filson
authors.forename: Lucia
authors.initials: L
authors.lastname: Maini
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Netherton
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.forename: John R
authors.initials: JR
authors.lastname: Scheffer
authors.forename: Carl
authors.initials: C
authors.lastname: Scott
authors.forename: Wujiong
authors.initials: W
authors.lastname: Xia