Syntheses, absorption spectra, luminescence properties, and electrochemical behavior of mono- and binuclear ruthenium(II) complexes of isomeric bis(2-pyridyl)pyrazines

Journal Article · Wed Jun 28 04:00:00 EDT 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00312a013· OSTI ID:5104158

Campagna, S ^[1]; Denti, G; De Rosa, G; Sabatino, L ^[2]; Ciano, M; Balzani, V ^[3]

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1. Univ. of Messina (Italy)
2. Univ. of Calabria, Rende (Italy)
3. FRAE-CNR Institute, Bologna (Italy)

The complexes Ru(2,3-dpp)(CO){sub 2}Cl{sub 2}, Ru(2,5-dpp)(CO){sub 2}Cl{sub 2}, ({mu}-2,3-dpp)(Ru(CO){sub 2}Cl{sub 2}){sub 2}, and ({mu}-2,5-dpp)(Ru(CO){sub 2}Cl{sub 2}){sub 2}, where dpp is bis(2-pyridyl)pyrazine, have been synthesized and characterized. The absorption spectra (including their solvent dependence), luminescence spectra, luminescence decay, electrochemical behavior, and photochemical reactivity of the cited complexes have been investigated. For comparison purposes, the properties of the free ligands have also been studied. The absorption spectra of the complexes show ligand-centered (LC) bands in the UV region and broad metal-to-ligand (Ru {yields} dpp) charge-transfer (MLCT) bands in the visible region. The luminescence spectrum exhibited by each complex in rigid matrix at 77 K is similar in energy and shape to that exhibited by the correspondent free ligand. No correlation is observed between the energies of the MLCT absorption bands and the energies of the luminescence bands. On the basis of these results and of the relatively long luminescence lifetimes (10{sup {minus}4}-10{sup {minus}5} s in butyronitrile at 77 K), emission is assigned to a {sup 3}LC excited state. The Ru(2,5-dpp)(CO){sub 2}Cl{sub 2} complex is luminescent also in fluid solution at room temperature. Each complex undergoes irreversible oxidation near +2 V, not occurring for the free ligand, and a reversible one-electron reduction at potentials less negative than those of the free ligand reduction. The reduction potentials of the bimetallic complexes are less negative than those of the corresponding monometallic species in good correlation with the energies of the MLCT absorption bands. All the complexes examined are strongly photosensitive in fluid solution, with release of a CO ligand per metal unit. 45 refs., 8 figs., 3 tabs.

• OSTI ID: 5104158
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 28:13; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
ABSORPTION SPECTRA
AZINES
CHEMISTRY
COMPLEXES
DATA
ELECTROCHEMISTRY
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
LUMINESCENCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRAZINES
PYRIDINES
RUTHENIUM COMPLEXES
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPLEXES