Application of neutral iridium(I) N-heterocyclic carbene complexes in ortho-directed hydrogen isotope exchange.

Bench-stable complexes of the type [Ir(COD)(NHC)Cl] (NHC = N-heterocyclic carbene) have been investigated within the field of hydrogen isotope exchange. By employing a sterically encumbered NHC within such complexes and catalyst loadings of only 5 mol%, moderate to high deuterium incorporations were achieved across a range of aromatic ketones and nitrogen-based heterocycles. The simple and synthetically accessible catalysts reported herein present alternatives to phosphine-based species and increase the available labelling systems with respect to established iridium-based isotope exchange methodologies.