Spontaneous oxidation of water to oxygen by the mixed-valence µ-oxo ruthenium dimer L ₂ (H ₂ O)Ru III –O–Ru IV (OH)L ₂ (L = 2,2′-bipyridyl-5,5′-dicarboxylic acid)

The mixed-valence µ-oxo ruthenium dimer L2(H2O)RuIII–O–RuIV(OH)L2, where L = 2,2′-bipyridyl-5,5′-dicarboxylic acid, converts spontaneously into L2(H2O)RuIII–O–RuIII(H2O)L2 under simultaneous oxidation of water to oxygen under conditions where the driving force of the reaction is less than 0.1 eV per transferred electron.