title: Isolation and characterization of phenyl viologen as a radical cation and neutral molecule.
abstract: The chemical synthesis, isolation, and characterization of phenyl viologen (PV) as a dication, radical cation, and neutral species are described. Single-crystal X-ray diffraction of PV(2+)2Cl(-.)2H2O and PV(.+)PF(6)(-).pyridine reveals the expected differences in bond lengths and also a structural change from two coplanar central rings in PV(.+) to a twist of 36 degrees between the two central rings in PV(2+). The phenyl viologen radical cation exhibits behavior characteristic of many radical cations, including weak pi-dimerization in the solid state and reversible pi-dimerization in solution. Electrical conductivity measurements of neutral phenyl viologen, the first such measurements of a neutral viologen, reveal that it is a significantly better conductor than the radical cation. Differences in geometric relaxation during charge transfer offer a possible explanation for the higher conductivity of the neutral viologen.
authors.affiliation: Center for Materials Innovation and Department of Chemistry, Washington University, St. Louis, MO 63130, USA.
authors.forename: William W
authors.initials: WW
authors.lastname: Porter
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Vaid
mesh_terms: D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D014755:Viologens / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; D014755:Viologens; C502066:phenyl viologen