New dinuclear asymmetric complexes of ruthenium of the type : [(bpy)₂Ru(5-CNphen)Ru(NH₃)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)₂Ru(5-CNphen)Ru(NH₃)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)₂Ru^II(5-CNphen)Ru^III(NH₃)₅]⁵⁺, pointing to the occurrence of intramolecular electron transfer processes that follow light excitation. From spectral data of 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.