Multimetallic ruthenium(II) complexes based on biimidazole and bibenzimidazole: Effect of dianionic bridging ligands on Redox and spectral properties
- Univ. of North Carolina, Charlotte (USA)
The preparation and properties of ruthenium(II) complexes containing the ligands 2,2{prime}-biimidazole (BiImH{sub 2}), 2,2{prime}-bibenzimidazole (BiBzImH{sub 2}), and 2,2{prime}-bipyridine (bpy) are reported. The complexes described are ((Ru(bpy){sub 2}){sub 2}BiIm){sup 2+} and the series (Ru-(bpy){sub n}(BiImH{sub 2}){sub 3{minus}n}){sup 2+}, (Ru(bpy){sub n}(BiBzImH{sub 2}){sub 3{minus}n}){sup 2+}, and (Ru(bpy){sub n}(BiBzImRu(bpy){sub 2}){sub 3{minus}n}){sup 2+}, n = 0-2. The redox potential for the first Ru{sup 3+/2+} couple shifted negatively from 1.26 to {minus}0.26 V vs SSCE as bpy ligands were replaced by BiImH{sub 2}, BiBzImH{sub 2}, and BiBzImRu(bpy){sub 2} ligands. Reductions were found in the {minus}1.5- to {minus}1.6-V range for complexes containing bypyridine ligands, but none were observed out to {minus}2.0 V for (Ru(BiImH{sub 2}){sub 3}){sup 2+} or (Ru(BiBzImH{sub 2}){sub 3}){sup 2+}. The complexes absorbed energy in the visible and UV regions of the spectrum and emitted radiation, with the exception of the tetrametallic species, in the 600-800-nm region. Estimates of the excited-state redox potentials revealed that the excited-state species were powerful reductants, but were weak oxidants. The (Ru{sup III}-(BiBzImRu{sup II}(bpy){sub 2}){sub 3}){sup 3+} cation absorbed in the near-infrared region at 12.2 {times} 10{sup 3} cm{sup {minus}1} in acetonitrile, but the absorption disappeared upon reduction to (Ru{sup II}(BiBzImRu{sup II}(bpy){sub 2}){sub 3}){sup 2+}. The position of the absorption manifold maximum varied linearly with the static and optical dielectric constant of the solvent. 45 refs., 12 figs., 3 tabs.
- OSTI ID:
- 6902091
- Journal Information:
- Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:2; ISSN 0020-1669; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ruthenium(II) cluster complexes: a series of homooligonuclear complexes based on bidentate bridging ligands
Three new extended Preyssler-type polyoxometalates modified by transition metal-2,2 Prime -biimidazole complexes
Related Subjects
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
ABSORPTION SPECTRA
CHEMICAL REACTIONS
COMPLEXES
DATA
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REDOX REACTIONS
RUTHENIUM COMPLEXES
SPECTRA
TRANSITION ELEMENT COMPLEXES