The activation of abundant molecules such as hydrocarbons and atmospheric nitrogen (N2) remains a challenge because these molecules are often inert. The formation of carbon–nitrogen bonds from N2 typically has required reactive organic precursors that are incompatible with the reducing conditions that promote N2 reactivity1, which has prevented catalysis. Here we report a diketiminate-supported iron system that sequentially activates benzene and N2 to form aniline derivatives. The key to this coupling reaction is the partial silylation of a reduced iron–dinitrogen complex, followed by migration of a benzene-derived aryl group to the nitrogen. Further reduction releases N2-derived aniline, and the resulting iron species can re-enter the cyclic pathway. Specifically, we show that an easily prepared diketiminate iron bromide complex2 mediates the one-pot conversion of several petroleum-derived arenes into the corresponding silylated aniline derivatives, by using a mixture of sodium powder, crown ether, trimethylsilyl bromide and N2 as the nitrogen source. Numerous compounds along the cyclic pathway are isolated and crystallographically characterized, and their reactivity supports a mechanism for sequential hydrocarbon activation and N2 functionalization. This strategy couples nitrogen atoms from N2 with abundant hydrocarbons, and maps a route towards future catalytic systems.
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Materials and methods, experimental procedures, useful information, spectra and mass spectrometry data are available in Supplementary Information. Raw data are available from the corresponding author on reasonable request. The crystallographic datasets generated during the current study are publicly available from the Cambridge Crystallographic Data Centre (CCDC) repository at https://www.ccdc.cam.ac.uk/structures/ with CCDC numbers 1937999, 1978000, 1938001, 1938002, 1939265, 1939266 and 1966313.
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This research was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Program under award DE-SC0020315 (final phases of the work), and by the National Institutes of Health under award R01 GM-065313 (initial phases of the work). Additional fellowship support came from the National Institutes of Health (F31 GM-116463 to S.F.M.), the Netherlands Organization for Scientific Research (Rubicon Postdoctoral Fellowship 680-50-1517 to D.L.J.B.) and the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (internship for C.J.V.H.). This work was supported in part by the facilities and staff of the Yale University Faculty of Arts and Sciences High Performance Computing Center, which was partially funded by the National Science Foundation under award CNS-08-21132. We thank N. Hazari, J. Mayer, J. Ellman and K. Skubi for critical feedback on the manuscript.
The authors declare no competing interests.
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McWilliams, S.F., Broere, D.L.J., Halliday, C.J.V. et al. Coupling dinitrogen and hydrocarbons through aryl migration. Nature 584, 221–226 (2020). https://doi.org/10.1038/s41586-020-2565-5