Sequential Deoxygenation of CO(2) and NO(2)(–) via Redox-Control of a Pyridinediimine Ligand with a Hemilabile Phosphine

[Image: see text] The deoxygenation of environmental pollutants CO(2) and NO(2)(–) to form value-added products is reported. CO(2) reduction with subsequent CO release and NO(2)(–) conversion to NO are achieved via the starting complex Fe((PPh)PDI)Cl(2) (1). 1 contains the redox-active pyridinediimine (PDI) ligand with a hemilabile phosphine located in the secondary coordination sphere. 1 was reduced with SmI(2) under a CO(2) atmosphere to form the direduced monocarbonyl Fe((PPh)PDI)(CO) (2). Subsequent CO release was achieved via oxidation of 2 using the NO(x)(–) source, NO(2)(–). The resulting [Fe((PPh)PDI)(NO)](+) (3) mononitrosyl iron complex (MNIC) is formed as the exclusive reduction product due to the hemilabile phosphine. 3 was investigated computationally to be characterized as {FeNO}(7), an unusual intermediate-spin Fe(III) coupled to triplet NO(–) and a singly reduced PDI ligand.