Formic Acid Acting as an Efficient Oxygen Scavenger in Four-Electron Reduction of Oxygen Catalyzed by a Heterodinuclear Iridium−Ruthenium Complex in Water

A heterodinuclear iridium−ruthenium complex [Ir<sup>III</sup>(Cp*)(H<sub>2</sub>O)(bpm)Ru<sup>II</sup>(bpy)<sub>2</sub>](SO<sub>4</sub>)<sub>2</sub> (Cp* = η<sup>5</sup>-pentamethyl-cyclopentadienyl, bpm = 2,2′-bipyrimidine, bpy = 2,2′-bipyridine) acts as an effective catalyst for removal of dissolved O<sub>2</sub> by the four-electron reduction of O<sub>2</sub> with formic acid in water at an ambient temperature.