title: Resonating valence bond ground state in oxygen-functionalized phenalenyl-based neutral radical molecular conductors.
abstract: We report the preparation, crystallization, and solid-state characterization of the first two members of a new family of spiro-bis(1,9-disubstituted phenalenyl)boron neutral radicals based solely on oxygen functionalization, and we show that this strategy significantly lowers the electrochemical disproportionation potentials (DeltaE), in comparison with other spiro-bis(1,9-disubstituted phenalenyl)boron salts. In the solid state, these radicals pack in a continuous array of pi-pi-stacked phenalenyl units with very short intermolecular carbon...carbon contacts. These two radicals are among the most highly conducting neutral organic solids, with room temperature conductivities reaching 0.3 S/cm. Magnetic susceptibility measurements show that the radicals do not exist as isolated free radicals, and there is significant spin-spin interaction between the molecules in the solid state as expected from the crystal structures and the calculated band structures; the solid-state properties are best rationalized in terms of the resonating valence bond model.
authors.affiliation: Departments of Chemistry, Chemical & Environmental Engineering, University of California, Riverside, CA 92521-0403, USA.
authors.forename: Swadhin K
authors.initials: SK
authors.lastname: Mandal
authors.forename: Satyabrata
authors.initials: S
authors.lastname: Samanta
authors.forename: Mikhail E
authors.initials: ME
authors.lastname: Itkis
authors.forename: Dell W
authors.initials: DW
authors.lastname: Jensen
authors.forename: Robert W
authors.initials: RW
authors.lastname: Reed
authors.forename: Richard T
authors.initials: RT
authors.lastname: Oakley
authors.forename: Fook S
authors.initials: FS
authors.lastname: Tham
authors.forename: Bruno
authors.initials: B
authors.lastname: Donnadieu
authors.forename: Robert C
authors.initials: RC
authors.lastname: Haddon