Reduction of CO 2 by Pyridine Monoimine Molybdenum Carbonyl Complexes: Cooperative Metal–Ligand Binding of CO 2

[( Ar PMI)Mo(CO) 4 ] complexes (PMI=pyridine monoimine; Ar=Ph, 2,6‐di‐ iso ‐propylphenyl) were synthesized and their electrochemical properties were probed with cyclic voltammetry and infrared spectroelectrochemistry (IR‐SEC). The complexes undergo a reduction at more positive potentials than the related [(bipyridine)Mo(CO) 4 ] complex, which is ligand based according to IR‐SEC and DFT data. To probe the reaction product in more detail, stoichiometric chemical reduction and subsequent treatment with CO 2 resulted in the formation of a new product that is assigned as a ligand‐bound carboxylate, [(   i Pr   2 Ph PMI)Mo(CO) 3 (CO 2 )] 2− , by NMR spectroscopic methods. The CO 2 adduct [(   i Pr   2 Ph PMI)Mo(CO) 3 (CO 2 )] 2− could not be isolated and fully characterized. However, the CC coupling between the CO 2 molecule and the PDI ligand was confirmed by X‐ray crystallographic characterization of one of the decomposition products of [(   i Pr   2 Ph PMI)Mo(CO) 3 (CO 2 )] 2− .