title: Neutral-Type One-Dimensional Mixed-Valence Halogen-Bridged Platinum Chain Complexes with Large Charge-Transfer Band Gaps.
abstract: One-dimensional (1D) electronic systems have attracted significant attention for a long time because of their various physical properties. Among 1D electronic systems, 1D halogen-bridged mixed-valence transition-metal complexes (the so-called MX chains) have been thoroughly studied owing to designable structures and electronic states. Here, we report the syntheses, structures, and electronic properties of three kinds of novel neutral MX-chain complexes. The crystal structures consist of 1D chains of Pt-X repeating units with (1R,2R)-(-)-diaminocychlohexane and CN(-) in-plane ligands. Because of the absence of a counteranion, the neutral MX chains have short interchain distances, so that strong interchain electronic interaction is expected. Resonance Raman spectra and diffuse-reflectance UV-vis spectra indicate that their electronic states are mixed-valence states (charge-density-wave state: Pt(2+)···X-Pt(4+)-X···Pt(2+)···X-Pt(4+)-X···). In addition, the relationship between the intervalence charge-transfer (IVCT) band gap and the degree of distortion of the 1D chain shows that the neutral MX chains have a larger IVCT band gap than that of cationic MX-chain complexes. These results provide new insight into the physical and electronic properties of 1D chain compounds.
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Otake
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Otsubo
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), SPring-8 , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Sugimoto
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), SPring-8 , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Fujiwara
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.|Institute for Integrated Cell-Material Sciences, Kyoto University , Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.|INAMORI Frontier Research Center, Kyushu University , Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa