A series of water-soluble Ru2 5+ complexes of the type Ru2(O2CCH3)3­(L)Cl where L = 2,3,4,5,6-F5ap, 2,4,6-F3ap, 2-Fap, ap, 2-Meap, 2,6-Me2ap, or 2,4,6-Me3ap, where ap is the anilinopyridinate anion, have been characterized as to their structural and physicochemical properties in H2O and DMSO. Five of the newly synthesized complexes were structurally characterized, and the Ru–Cl bond lengths range from 2.477 to 2.544 Å while the Ru–Ru bond lengths range from 2.2838 to 2.2935 Å. The UV–vis spectra of each compound are characterized by three absorption bands in both H2O and DMSO, the intensity and position of which vary with both the type of bridging ligand and the solvent. The seven examined Ru2 5+ complexes exist as 1:1 electrolytes in water, and each undergoes a reversible one-electron reduction assigned to Ru2 5+/Ru2 4+ in both investigated solvents. A second irreversible reduction attributed to Ru2 4+/Ru2 3+ is also observed for each compound at more negative potentials in DMSO. A linear free energy relationship exists between the sum of the Hammett substituent constants (Σσ) on the ap-type bridging ligand and the wavenumber of an absorption band for the Ru2 5+ complexes. A linear relationship is also seen between Σσ and measured E 1/2 values for the Ru2 5+/Ru2 4+ process in water containing 0.1 M KCl, but little to no effect is seen between the specific bridging ligand and the structural features of the investigated compounds.