A unique mode of stoichiometric CO, activation and reductive splitting based on metal ligand-cooperation is described. The novel Ir hydride complexes [(Bu-t-PNP*)Ir(H)(2)] (2) (Bu-t-PNP*, deprotonated Bu-t-PNP ligand) and [(Bu-t-PNP)Ir(H)] (3) react with CO, to give the dearomatized complex [(Bu-t-PNP*)Ir(CO)] (4) and water. Mechanistic studies have identified an adduct in which CO2 is bound to the ligand and metal, [(Bu-t-PNP-COO)Ir(H)(2)] (5), and a di-CO2 iridacycle [(Bu-t-PNP)Ir(H)(C2O4-kappa(C,O))] (6). DFT calculations confirm the formation of 5 and 6 as reversibly formed side products, and suggest an eta(1)-CO2 intermediate leading to the thermodynamic product 4. The calculations support a metal ligand-cooperation pathway in which an internal deprotonation of the benzylic position by the eta(1)-CO2 ligand leads to a carboxylate intermediate, which further reacts with the hydride ligand to give complex 4 and water.