Coupling dinitrogen and hydrocarbons through aryl migration.

Abstract

A persistent challenge in chemistry is to activate abundant, yet inert molecules such as hydrocarbons and atmospheric N2. In particular, forming C–N bonds from N2 typically requires a reactive organic precursor1, which limits the ability to design catalytic cycles. Here, we report an diketiminate-supported iron system that is able to sequentially activate benzene and N2 to form aniline derivatives. The key to this new coupling reaction is the partial silylation of a reduced iron-N2 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 complex2 can mediate the one-pot conversion of several petroleum-derived compounds into the corresponding silylated aniline derivatives using N2 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 N2 functionalization step. This strategy incorporates nitrogen atoms from N2 directly into abundant hydrocarbons.