title: Charge localization in a 17-bond mixed-valence quinone radical anion.
abstract: Optical spectra in dimethylformamide are reported for the radical anions of benzoquinone, its tetramethyl and tetrachloro analogues, and tetra-ortho-alkyl derivatives of biphenyl, stilbene, terphenyl, quadriphenyl, and 1,4-bis(2-phenylethenyl)benzene quinones. The first absorption bands for all but the quadriphenyl quinone show vibrational fine structure, demonstrating that they are delocalized (Class III) mixed-valence compounds. The quadriphenyl quinone radical anion shows a wide Gaussian-shaped band having a band maximum that is strongly dependent on solvent, typical of localized (Class II) mixed-valence compounds. The simple O charge-bearing unit of these compounds maintains charge delocalization in examples with unusually large bridges.
authors.affiliation: Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706-1396, USA.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Nelsen
authors.forename: Michael N
authors.initials: MN
authors.lastname: Weaver
authors.forename: João P
authors.initials: JP
authors.lastname: Telo