title: Continuous control of optical gaps in quasi-one-dimensional bromide-bridged platinum complexes by utilizing chemical pressure.
abstract: The optical gap in a series of bromo-bridged platinum chain complexes, [Pt(en)2Br](C(n)-Y)2·H2O (en = ethylenediamine; C(n)-Y = dialkyl sulfosuccinate; n = the number of carbon atoms), was controlled by using chemical pressure. From the single-crystal structure, [Pt(en)2Br](C6-Y)2·H2O is in a mixed-valence state at 200 K. In addition, Pt-Pt distances decreased with an increase in n or with a decrease in the temperature. Continuous decreases in the optical gaps upon cooling were observed for n = 5, 7. The smallest gap of 1.20 eV was observed for n = 7 at 50 K. For n = 12, the complex was still in a mixed-valence state at 5 K, although the Pt-Pt distance was quite short. This is probably because of the energetic mismatch between 5dz(2) orbitals of the Pt ions and 4pz orbitals of the Br ions.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University , 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Kumagai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iguchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Takaishi
authors.forename: Brian K
authors.initials: BK
authors.lastname: Breedlove
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamashita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsuzaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okamoto
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kato
authors.forename: Masaki
authors.initials: M
authors.lastname: Takata