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Taming phosphorus mononitride


Phosphorus mononitride (PN) only has a fleeting existence on Earth, and molecular precursors for the release of this molecule under mild conditions in solution have remained elusive. Here we report the synthesis of an anthracene-based precursor—an anthracene moiety featuring an azidophosphine bridge across its central ring—that dissociates into dinitrogen, anthracene and P≡N in solution with a first-order half-life of roughly 30 min at room temperature. Heated under reduced pressure, this azidophosphine–anthracene precursor decomposes in an explosive fashion at around 42 °C, as demonstrated in a molecular-beam mass spectrometry study. The precursor is also shown to serve as a PN transfer reagent in the synthesis of an Fe–NP coordination complex, through ligand exchange with its Fe–N2 counterpart. The terminal N-bonded complex was found to be energetically preferred, compared to its P-bonded linkage isomer, owing to a significant covalent Fe–pnictogen bond character and an associated less unfavourable Pauli repulsion in the metal–ligand interaction.

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Fig. 1: Selected PN-containing molecules and transition-metal complexes with given PN bond distances.
Fig. 2: Synthesis, structure and decomposition of N3PA.
Fig. 3: Computed decomposition pathways of N3PA.
Fig. 4: Synthesis, structure and spectroscopic characterization of FeN2 and FeNP.
Fig. 5: Isomerization of the PN ligand in [(dppe)Fe(Cp*)(NP)]+ and analysis of the bonding situation.

Data availability

All relevant data generated and analysed during this study, including crystal structures, NMR, IR, molecular-beam mass spectrometry spectra and optimized coordinates for all calculated compounds, are included in this Article and its Supplementary Information, and are also available from the authors upon reasonable request. Crystallographic data for the structures reported in this Article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2098667 (N3PA, 8), 2098666 (FeN2, 9) and 2098665 (FeNP, 10). Copies of the data can be obtained free of charge via


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A.K.E. thanks the Alexander von Humboldt Foundation for a Feodor Lynen postdoctoral fellowship. This material is based on research supported by the National Science Foundation, under No. CHE-1955612. We thank all MIT DCIF staff members and C. Anklin (Bruker) for technical support with NMR measurements, as well as M. C. McCarthy (Harvard CfA), R. J. Gilliard (University of Virginia) and D. L. M. Suess (MIT) for fruitful discussion.

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Authors and Affiliations



A.K.E. conducted all experiments, carried out the computations of the potential energy surfaces and analysed the data. M.-L.Y.R. and P.M. collected all diffraction data and refined the structures. M.Y. collected all Mössbauer data. G.B. analysed the bonding situation in [(dppe)Fe(Cp*)(NP)][BArF24]. C.C.C. conceptualized the PN precursor and assisted in the design of experiments. A.K.E. wrote the manuscript with input from all authors.

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Correspondence to Christopher C. Cummins.

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Nature Chemistry thanks the anonymous reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–31, Discussion and Tables 1–10.

Supplementary Data 1

Crystallographic data for the compound N3PA; CCDC 2098667.

Supplementary Data 2

Crystallographic data for the compound FeN2; CCDC 2098666.

Supplementary Data 3

Crystallographic data for the compound FeNP; CCDC 2098665.

Supplementary Data 4

Cartesian coordinates and electronic energies for all structures depicted in Fig. 3.

Supplementary Data 5

Cartesian coordinates and electronic energies for all structures depicted in Fig. 5.

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Eckhardt, A.K., Riu, ML.Y., Ye, M. et al. Taming phosphorus mononitride. Nat. Chem. 14, 928–934 (2022).

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