title: 3,4-Dithiaphosphole and 3,3',4,4'-tetrathia-1,1'-biphosphole π-conjugated systems: S makes the impact.
abstract: Conjugated systems based on phospholes and 1,1'-biphospholes bearing 3,4-ethylenedithia bridges have been prepared using the Fagan-Nugent route. The mechanism of this organometallic route leading to intermediate zirconacyclopentadienes has been investigated by using theoretical calculations. This study revealed that the oxidative coupling leading to zirconacyclopentadienes is favored over oxidative addition within the S-C≡C bond both thermodynamically and kinetically. The impact of the presence of the S atoms on the optical and electrochemical behavior of the phospholes and 1,1'-biphospholes has been systematically evaluated both experimentally and theoretically. A comparison with their "all-carbon" analogues is provided. Of particular interest, this comparative study revealed that the introduction of S atoms has an impact on the electronic properties of phosphole-based conjugated systems. A decrease of the HOMO-LUMO separation and a stabilization of the LUMO level were observed. These general trends are also observed with 1,1'-biphospholes exhibiting σ-π conjugation. The P atom of the 3,4-ethylenedithiaphospholes can be selectively oxidized by S(8) or O(2). These P modifications result in a lowering of the HOMO-LUMO separation as well as an increase of the reduction and oxidation potentials. The S atoms of the 3,4-ethylenedithia bridge of the 2,5-phosphole have been oxidized using m-chloroperoxybenzoic acid. The resulting 3,4-ethylenesulfoxide oxophosphole was characterized by an X-ray diffraction study. Experimental and theoretical studies show that this novel chemical manipulation results in an increase of the HOMO-LUMO separation and an important decrease of the LUMO level. The electropolymerization of 2-thienyl-capped 3,4-ethylenedithiathioxophosphole and 1,1'-biphosphole is reported. The impact of the S substituents on the polymer properties is discussed.
authors: Sciences Chimiques de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France.
authors: Omrane
authors: O
authors: Fadhel
authors: Zoltán
authors: Z
authors: Benkö
authors: Michael
authors: M
authors: Gras
authors: Valérie
authors: V
authors: Deborde
authors: Damien
authors: D
authors: Joly
authors: Christophe
authors: C
authors: Lescop
authors: László
authors: L
authors: Nyulászi
authors: Muriel
authors: M
authors: Hissler
authors: Régis
authors: R
authors: Réau