Coupling Dinitrogen and Hydrocarbons through Aryl Migration

A persistent challenge in chemistry is to activate abundant, yet inert molecules such as hydrocarbons and atmospheric N(2). In particular, forming C–N bonds from N(2) typically requires a reactive organic precursor(1), which limits the ability to design catalytic cycles. Here, we report an diketiminate-supported iron system that is able to sequentially activate benzene and N(2) to form aniline derivatives. The key to this new coupling reaction is the partial silylation of a reduced iron-N(2) complex, which is followed by migratory insertion of a benzene-derived phenyl group to the nitrogen. Further reduction releases the nitrogen products, and the resulting iron species can re-enter the cyclic pathway. Using a mixture of sodium powder, crown ether, and trimethylsilyl bromide, an easily prepared diketiminate iron bromide complex(2) can mediate the one-pot conversion of several petroleum-derived compounds into the corresponding silylated aniline derivatives using N(2) as the nitrogen source. Numerous compounds along the cyclic pathway have been isolated and crystallographically characterized; their reactivity outlines the mechanism including the hydrocarbon activation step and the N(2) functionalization step. This strategy incorporates nitrogen atoms from N(2) directly into abundant hydrocarbons.