title: Synthesis, crystal structure, and physical properties of sterically unprotected hydrocarbon radicals.
abstract: We have prepared and isolated neutral polycyclic hydrocarbon radicals. A butyl-substituted radical gave single crystals, in which a π-dimeric structure, not a σ-bonded dimer, was observed, even though steric protection was absent. Thermodynamic stabilization due to the highly spin-delocalized structure contributes effectively to the suppression of σ-bond formation.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. kubo@chem.sci.osaka-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kubo
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Katada
authors.forename: Akihiro
authors.initials: A
authors.lastname: Shimizu
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Hirao
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Sato
authors.forename: Takeji
authors.initials: T
authors.lastname: Takui
authors.forename: Mikio
authors.initials: M
authors.lastname: Uruichi
authors.forename: Kyuya
authors.initials: K
authors.lastname: Yakushi
authors.forename: Robert C
authors.initials: RC
authors.lastname: Haddon