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Spectroscopic and electrochemical properties of dimeric ruthenium(II) diimine complexes and determination of their excited state redox properties

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00243a023· OSTI ID:6538610
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The complexes Ru(bpy)/sub 2/(ppz)/sup 2 +/ and ((bpy)/sub 2/Ru(ppz)Ru(bpy)/sub 2/)/sup 4 +/, where ppz is the planar ligand 4',7'-phenanthrolino-5',6':5,6-pyrazine, have been prepared and characterized. Resonance Raman spectra establish that the visible spectra of Ru(bpy)/sub 2/L/sup 2 +/ and ((bpy)/sub 2/Ru-L-Ru(bpy)/sub 2/)/sup 4 +/ complexes, where L is a bis-diimine, in general, are composed of MLCT transitions which terminate in the ..pi..* orbitals localized on the different ligands. The luminescence, which is detectable at room temperature in fluid solutions of both the mono- and bimetallic complexes, can be assigned as a L(..pi..*) ..-->.. Ru(II) t/sub 2/ transition. An approximate but general correlation between the lower energy MLCT absorption maximum and the emission maximum suggests that in many other bimetallic complexes of Ru(II) the emission energy is shifted beyond usual detection limits. Analysis of the emission and electrochemical data indicates that the MLCT states of bridged 2,3-dipyridylpyrazine (dpp) and ppz dimeric complexes are weak reductants but very strong oxidants. The implications of this general pattern of excited state redox potentials are discussed.
Research Organization:
City Univ. of New York, Flushing
OSTI ID:
6538610
Journal Information:
J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:9; ISSN JACSA
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
400500 -- Photochemistry
ABSORPTION SPECTROSCOPY
AZINES
BIPYRIDINES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
DIMERS
EFFICIENCY
ELECTROCHEMISTRY
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
IMINES
INFORMATION
LASER SPECTROSCOPY
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
QUANTUM EFFICIENCY
RAMAN SPECTRA
RAMAN SPECTROSCOPY
REDOX POTENTIAL
REDOX REACTIONS
RUTHENIUM COMPLEXES
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
VOLTAMETRY