title: Dinuclear asymmetric ruthenium complexes with 5-cyano-1,10-phenanthroline as a bridging ligand.
abstract: New dinuclear asymmetric ruthenium complexes of the type [(bpy)(2)Ru(5-CNphen)Ru(NH(3))(5)](4+/5+) (bpy = 2,2'-bipyridine; 5-CNphen = 5-cyano-1,10-phenanthroline) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. The structure of the cation [(bpy)(2)Ru(5-CNphen)Ru(NH(3))(5)](4+) has been determined by X-ray diffraction. The mononuclear precursor [Ru(bpy)(2)(5-CNphen)](2+) has also been prepared and studied; while its properties as a photosensitizer are similar to those of [Ru(bpy)(3)](2+), its luminescence at room temperature is quenched by a factor of 5 in the mixed-valent species [(bpy)(2)Ru(II)(5-CNphen)Ru(III)(NH(3))(5)](5+), pointing to the occurrence of intramolecular electron-transfer processes that follow light excitation. From spectral data for the metal-to-metal charge-transfer transition Ru(II) --> Ru(III) in this latter complex, a slight electronic interaction (H(AB) = 190 cm(-1)) is disclosed between both metallic centers through the bridging 5-CNphen.
authors.affiliation: Instituto de Química Física, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 491, (T4000INI) San Miguel de Tucumán, Republic of Argentina.
authors.forename: María G
authors.initials: MG
authors.lastname: Mellace
authors.forename: Florencia
authors.initials: F
authors.lastname: Fagalde
authors.forename: Néstor E
authors.initials: NE
authors.lastname: Katz
authors.forename: Irma G
authors.initials: IG
authors.lastname: Crivelli
authors.forename: Alvaro
authors.initials: A
authors.lastname: Delgadillo
authors.forename: Ana María
authors.initials: AM
authors.lastname: Leiva
authors.forename: Bárbara
authors.initials: B
authors.lastname: Loeb
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Garland
authors.forename: Ricardo
authors.initials: R
authors.lastname: Baggio