title: Electronic coupling between two amine redox sites through the 5,5'-positions of metal-chelating 2,2'-bipyridines.
abstract: Electron delocalization of new mixed-valent (MV) systems with the aid of lateral metal chelation is reported. 2,2'-Bipyridine (bpy) derivatives with one or two appended di-p-anisylamino groups on the 5,5'-positions and a coordinated [Ru(bpy)(2)] (bpy = 2,2'-bipyridine), [Re(CO)(3)Cl], or [Ir(ppy)(2)] (ppy = 2-phenylpyridine) component were prepared. The single-crystal molecular structure of the bis-amine ligand without metal chelation is presented. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic techniques and DFT/TDDFT calculations. Compounds with two di-p-anisylamino groups were oxidized by a chemical or electrochemical method and monitored by near-infrared (NIR) absorption spectral changes. Marcus-Hush analysis of the resulting intervalence charge-transfer transitions indicated that electron coupling of these mixed-valent systems is enhanced by metal chelation and that the iridium complex has the largest coupling. TDDFT calculations were employed to interpret the NIR transitions of these MV systems.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
authors.forename: Hai-Jing
authors.initials: HJ
authors.lastname: Nie
authors.forename: Xialing
authors.initials: X
authors.lastname: Chen
authors.forename: Chang-Jiang
authors.initials: CJ
authors.lastname: Yao
authors.forename: Yu-Wu
authors.initials: YW
authors.lastname: Zhong
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Hutchison
authors.forename: Jiannian
authors.initials: J
authors.lastname: Yao