title: Electrical properties and electronic states of molecular conductors based on unsymmetrical organometallic-dithiolene gold(III) complexes.
abstract: The electronic properties of cation radical salts derived from organometallic mixed-ligand complexes [(ppy)Au(S-S)](ppy- = C-dehydro-2-phenylpyridine(-); S-S(2-) = dithiolene ligand) with Au(III)-C sigma-bond were investigated. A 2:1 salt complex [(ppy)Au(C8H4S8)]2[PF6] (C8H4S8(2-) = 2-((4,5-ethylenedithio)-1,3-dithiole-2-ylidene)-1,3-dithiole-4,5-dithiolate(2-)) exhibited semiconductive behavior under ambient pressure (rho rt = 2.6 Omega cm, Ea = 0.03 eV). Magnetic measurements show that it is a Mott insulator close to the metal-insulator boundary. Raman and infrared spectra have revealed that the complex has a quasi-one-dimensional dimeric structure consisting of uniformly charged donor molecules. The complex exhibits metallic behavior at pressures above 0.8 GPa. In contrast, a similar compound [(ppy)Au(C8H4S6O2)]2[BF4] (C8H4S6O2(2-) = 2-((4,5-ethylenedioxy)-1,3-dithiole-2-ylidene)-1,3-dithiole-4,5-dithiolate(2-)) is a band insulator.
authors.affiliation: RIKEN, JST-CREST, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan. kkubo@riken.jp
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kubo
authors.forename: Akiko
authors.initials: A
authors.lastname: Nakao
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Ishii
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tamura
authors.forename: Reizo
authors.initials: R
authors.lastname: Kato
authors.forename: Kyuya
authors.initials: K
authors.lastname: Yakushi
authors.forename: Gen-etsu
authors.initials: GE
authors.lastname: Matsubayashi