Versatile Hydrogen Reduction Mechanisms at Room Temperature

Chemists have been investigating the various reduction mechanisms of hydrogen since it is a prime contender as a next‐generation energy source. In this article, it reports iridium complexes capable of two different reduction mechanisms at room temperature—where H 2 is used as an electron source and/or a hydride source. First, the synthesis of an iridium‐amide complex is reported with a strongly electron‐donating C ‐coordinated amido ligand through the reaction of CO 2 with an amine, which uses H 2 as an electron source. Following that, the first example of the hydrogenation of a terpyridine ligand by the reaction with H 2 as an electron source and/or a hydride source is reported. Finally, the mechanisms are discussed by which H 2 behaves as a dual‐function reductant at room temperature, utilizing isotope experiments with 13 CO 2 and D 2 , as well as two crystal structures: an iridium‐amide complex and an iridium complex with a hydrogenated terpyridine ligand.