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A polyazine ligand, 5,5′-di(1-butyl-1,2,3-triazol-4-yl)-2,2′-bipyridine(Bu-dtabpyH), has been prepared by a “click” reaction.The treatment of Bu-dtabpyH with [Ru(bpy)2Cl2] affords complex [Ru(bpy)2(Bu-dtabpyH)]2+(bpy= 2,2′-bipyridine), which has been characterized by single-crystalX-ray analysis. The reaction of [Ru(bpy)2(Bu-dtabpyH)]2+with another equivalent of [Ru(bpy)2Cl2] in the presence of AgOTf gives a redox-asymmetric bisrutheniumcomplex, [Ru(bpy)2(Bu-dtabpy)Ru(bpy)2]3+(Bu-dtabpy is the 4-deprotonated form of Bu-dtabpyH), with one rutheniumatom binding to the pyridin-4-yl bridge with a Ru–N bond andthe other with a Ru–C bond. This complex displays two Ru(II/III)redox couples at +0.79 and +1.28 V vs Ag/AgCl. After being transformedinto a mixed-valence species, [Ru(bpy)2(Bu-dtabpy)Ru(bpy)2]4+, by one-electron oxidation, it exhibits a moderatemetal-to-metal charge-transfer band around 1300 nm. Density functionaltheory and time-dependent density functional theory calculations havebeen carried out for the model complex [Ru(bpy)2(Me-dtabpy)Ru(bpy)2]3+and the mixed-valence state [Ru(bpy)2(Me-dtabpy)Ru(bpy)2]4+to complement theseexperimental results, where Me-dtabpy is the 4-deprotonated form of5,5′-di(1-methyl-1,2,3-triazol-4-yl)-2,2′-bipyridine. [ABSTRACT FROM AUTHOR]