Facile H/D Exchange at (Hetero)Aromatic Hydrocarbons Catalyzed by a Stable Trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex.

Earth-abundant metal pincer complexes have played an important role in homogeneous catalysis during the last ten years. Yet, despite intense research efforts, the synthesis of iron PCP pincer complexes has so far remained elusive. Here we report the synthesis of the first PCP functionalized iron complex [(PCP)FeCl] () and the reactivity of the corresponding -dihydride iron(II) dinitrogen complex [(PCP)Fe(H)N)] (). Complex is stable under an atmosphere of N and is highly active for hydrogen isotope exchange at (hetero)aromatic hydrocarbons under mild conditions (50 °C, N). With benzene- as the deuterium source, easily reducible functional groups such as esters and amides are well tolerated, contributing to the overall wide substrate scope (e.g., halides, ethers, and amines). DFT studies suggest a complex assisted σ-bond metathesis pathway for C(sp)-H bond activation, which is further discussed in this study.