Description:
<jats:title>Abstract</jats:title><jats:p>The iridium dihydride [Ir(H)<jats:sub>2</jats:sub>(<jats:italic>H</jats:italic>PNP)]<jats:sup>+</jats:sup> (PNP=N(CH<jats:sub>2</jats:sub>CH<jats:sub>2</jats:sub>P<jats:italic>t</jats:italic>Bu<jats:sub>2</jats:sub>)<jats:sub>2</jats:sub>) reacts with O<jats:sub>2</jats:sub> to give the unusual, square‐planar iridium(III) hydroxide [Ir(OH)(PNP)]<jats:sup>+</jats:sup> and water. Regeneration of the dihydride with H<jats:sub>2</jats:sub> closes a quasi‐catalytic synthetic oxygen‐reduction reaction (ORR) cycle that can be run several times. Experimental and computational examinations are in agreement with an oxygenation mechanism via rate‐limiting O<jats:sub>2</jats:sub> coordination followed by H‐transfer at a single metal site, facilitated by the cooperating pincer ligand. Hence, the four electrons required for the ORR are stored within the two covalent MH bonds of a mononuclear metal complex.</jats:p>