title: Synthesis, structure and physical properties of the first one-dimensional phenalenyl-based neutral radical molecular conductor.
abstract: We report the preparation, crystallization, and solid-state characterization of a benzyl-substituted spirobiphenalenyl radical. The crystal structure shows that the radical is monomeric in the solid state, with the molecules packed in an unusual one-dimensional (1-D) fashion that we refer to as a pi-step stack. This particular mode of 1-D stacking is forced on the lattice arrangement by the presence of the orthogonal phenalenyl units that were specifically incorporated to prevent the crystallization of low-dimensional structures. The structure shows that this strategy is effective, and neighboring molecules in the stack can only interact via the overlap of one pair of active (spin-bearing) carbon atoms per phenalenyl unit, leading to the pi-step structure in which the remaining four active carbon atoms per phenalenyl unit do not interact with nearest neighbor molecules. The magnetic susceptibility data in the temperature range 4-360 K may be fit to an antiferromagnetic Heisenberg S = 1/2 linear chain model with intrachain spin coupling J = -52.3 cm(-1). Despite the uniform stacking, the material has a room temperature conductivity of 1.4 x 10(-3) S/cm and is best described as a Mott insulator.
authors.affiliation: Department of Chemistry, University of California, Riverside, California 92521-0403, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Pal
authors.forename: M E
authors.initials: ME
authors.lastname: Itkis
authors.forename: R W
authors.initials: RW
authors.lastname: Reed
authors.forename: R T
authors.initials: RT
authors.lastname: Oakley
authors.forename: A W
authors.initials: AW
authors.lastname: Cordes
authors.forename: F S
authors.initials: FS
authors.lastname: Tham
authors.forename: T
authors.initials: T
authors.lastname: Siegrist
authors.forename: R C
authors.initials: RC
authors.lastname: Haddon