Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A crystalline aluminium–carbon-based ambiphile capable of activation and catalytic transfer of ammonia in non-aqueous media


Despite recent achievements in the field of frustrated Lewis pairs (FLPs) for small molecule activations, the reversible activation and catalytic transformations of N–H-activated ammonia remain a challenge. Here we report on a rare combination of an aluminium Lewis acid and a carbon Lewis base. A so-called hidden FLP consisting of a phosphorus ylide featuring an aluminium fragment in the ortho position of a phenyl ring scaffold is introduced. Although the formation of the Lewis acid/base adduct is observed in the solid state, which at first glance leads to formally quenched FLP reactivity, we show that the title compound readily reacts with non-aqueous ammonia thermoneutrally and splits the N–H bond reversibly at ambient temperature. In addition, NH3 transfer reactions mediated by a main-group catalyst are presented. This proof-of-principle study is expected to initiate further activities in utilizing N–H-activated ammonia as a readily available, atom-economical nitrogen source.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Synthesis of the aluminiumcarbon-based ambiphile 2.
Fig. 2: Reversible N–H activation of ammonia.
Fig. 3: Catalytic ammonia transfer reactions in benzene at RT (pressure = 1.1 bar; 20 mol% compound 2).
Fig. 4: Kinetic studies of the catalytic alkylation of benzylbromide.
Fig. 5: Computed reaction profile of the ammonia transfer to Ia.

Similar content being viewed by others

Data availability

The data that support the findings of this study are available within the paper and its Supplementary Information. Raw and unprocessed NMR, HRMS and gel permeation chromatography data are available from figshare ( Materials and methods, computational studies including cartesian coordinates and energies for the computed structures, experimental procedures, characterization data, NMR spectra and mass spectrometry data are available in the paper with further details in the Supplementary Information. Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers 2180947 (2) and 2180948 (3). For further crystallographic details see Supplementary Section 2. Copies of the data can be obtained free of charge via Source data are provided with this paper.


  1. Streiff, S. & Jérôme, F. Hydroamination of non-activated alkenes with ammonia: a holy grail in catalysis. Chem. Soc. Rev. 50, 1512–1521 (2021).

    Article  CAS  PubMed  Google Scholar 

  2. Werner, A. Coordination chemistry. Z. Anorg. Chem. 3, 267–330 (1893).

  3. Bezdek, M. J., Guo, S. & Chirik, P. J. Coordination-induced weakening of ammonia, water, and hydrazine X–H bonds in a molybdenum complex. Science 354, 730–733 (2016).

    Article  CAS  PubMed  Google Scholar 

  4. Bryan, E. G., Johnson, B. F. G. & Lewis, J. 1,1,2,2,2,2,3,3,3,3-Decacarbonyl-1-(η-cyclohexa-1,3-diene)-triangulo-triosmium: a novel intermediate in synthetic osmium cluster chemistry. J. Chem. Soc. Dalton Trans. (1977).

  5. Hillhouse, G. L. & Bercaw, J. E. Reactions of water and ammonia with bis (pentamethylcyclopentadienyl) complexes of zirconium and hafnium. J. Am. Chem. Soc. 106, 5472–5478 (1984).

    Article  CAS  Google Scholar 

  6. Casalnuovo, A. L., Calabrese, J. C. & Milstein, D. Rational design in homogeneous catalysis. Iridium(I)-catalyzed addition of aniline to norbornylene via nitrogen-hydrogen activation. J. Am. Chem. Soc. 110, 6738–6744 (1988).

    Article  CAS  Google Scholar 

  7. Holl, M. M. B., Wolczanski, P. T. & Van Duyne, G. D. The ladder structure of [(tert-BuCH2)2TaN]5·NH3·2C7H8 and its relationship to cubic tantalum nitride. J. Am. Chem. Soc. 112, 7989–7994 (1990).

    Article  Google Scholar 

  8. Braun, T. Oxidative addition of NH3 to a transition-metal complex: a key step for the metal-mediated derivatization of ammonia? Angew. Chem. Int. Ed. 44, 5012–5014 (2005).

    Article  CAS  Google Scholar 

  9. Zhao, J., Goldman, A. S. & Hartwig, J. F. Oxidative addition of ammonia to form a stable monomeric amido hydride complex. Science 307, 1080–1082 (2005).

    Article  CAS  PubMed  Google Scholar 

  10. Nakajima, Y., Kameo, H. & Suzuki, H. Cleavage of nitrogen–hydrogen bonds of ammonia induced by triruthenium polyhydrido clusters. Angew. Chem. Int. Ed. 45, 950–952 (2006).

    Article  CAS  Google Scholar 

  11. Morgan, E., MacLean, D. F., McDonald, R. & Turculet, L. Rhodium and iridium amido complexes supported by silyl pincer ligation: ammonia N−H bond activation by a [PSiP]Ir complex. J. Am. Chem. Soc. 131, 14234–14236 (2009).

    Article  CAS  PubMed  Google Scholar 

  12. Salomon, M. A., Jungton, A.-K. & Braun, T. Activation of ethylene and ammonia at iridium: C–H versus N–H oxidative addition. J. Chem. Soc. Dalton Trans. (2009).

  13. Ni, C., Lei, H. & Power, P. P. Reaction of M(II) diaryls (M = Mn or Fe) with ammonia to afford parent amido complexes. Organometallics 29, 1988–1991 (2010).

    Article  CAS  Google Scholar 

  14. Brown, R. M. et al. Ammonia activation by a nickel NCN–pincer complex featuring a non-innocent N-heterocyclic carbene: ammine and amido complexes in equilibrium. Angew. Chem. Int. Ed. 54, 6274–6277 (2015).

    Article  CAS  Google Scholar 

  15. Scheibel, M. G. et al. Homolytic N–H activation of ammonia: hydrogen transfer of parent iridium ammine, amide, imide, and nitride species. Inorg. Chem. 54, 9290–9302 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Margulieux, G. W., Bezdek, M. J., Turner, Z. R. & Chirik, P. J. Ammonia activation, H2 evolution and nitride formation from a molybdenum complex with a chemically and redox noninnocent ligand. J. Am. Chem. Soc. 139, 6110–6113 (2017).

    Article  CAS  PubMed  Google Scholar 

  17. LaPierre, E. A., Piers, W. E. & Gendy, C. Redox-state dependent activation of silanes and ammonia with reverse polarity (PCcarbeneP)Ni complexes: electrophilic vs. nucleophilic carbenes. J. Chem. Soc. Dalton Trans. 47, 16789–16797 (2018).

    Article  CAS  Google Scholar 

  18. Power, P. P. Main-group elements as transition metals. Nature 463, 171–177 (2010).

    Article  CAS  PubMed  Google Scholar 

  19. Weetman, C. & Inoue, S. The road travelled: after main-group elements as transition metals. ChemCatChem 10, 4213–4228 (2018).

    Article  CAS  Google Scholar 

  20. Hansmann, M. M. & Bertrand, G. Transition-metal-like behavior of main group elements: ligand exchange at a phosphinidene. J. Am. Chem. Soc. 138, 15885–15888 (2016).

    Article  CAS  PubMed  Google Scholar 

  21. Wang, Y. & Liu, C.-G. The use of main-group elements to mimic catalytic behavior of transition metals I: reduction of dinitrogen to ammonia catalyzed by bis(Lewis base)borylenium diradicals. Phys. Chem. Chem. Phys. 22, 28423–28433 (2020).

    Article  CAS  PubMed  Google Scholar 

  22. Frey, G. D., Lavallo, V., Donnadieu, B., Schoeller, W. W. & Bertrand, G. Facile splitting of hydrogen and ammonia by nucleophilic activation at a single carbon center. Science 316, 439–441 (2007).

    Article  CAS  PubMed  Google Scholar 

  23. Wang, Y. et al. Activation of ammonia by a carbene-stabilized dithiolene zwitterion. J. Am. Chem. Soc. 144, 16325–16331 (2022).

    Article  CAS  PubMed  Google Scholar 

  24. Yang, X. et al. Radical activation of N–H and O–H bonds at bismuth(II). J. Am. Chem. Soc. 144, 16535–16544 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Abbenseth, J., Townrow, O. P. E. & Goicoechea, J. M. Thermoneutral N−H bond activation of ammonia by a geometrically constrained phosphine. Angew. Chem. Int. Ed. 60, 23625–23629 (2021).

    Article  CAS  Google Scholar 

  26. Welch, G. C., Juan, R. R. S., Masuda, J. D. & Stephan, D. W. Reversible, metal-free hydrogen activation. Science 314, 1124–1126 (2006).

    Article  CAS  PubMed  Google Scholar 

  27. Stephan, D. W. & Erker, G. Frustrated Lewis pairs: metal-free hydrogen activation and more. Angew. Chem. Int. Ed. 49, 46–76 (2010).

    Article  CAS  Google Scholar 

  28. Stephan, D. W. Frustrated Lewis pairs. J. Am. Chem. Soc. 137, 10018–10032 (2015).

    Article  CAS  PubMed  Google Scholar 

  29. Stephan, D. W. Frustrated Lewis pairs: from concept to catalysis. Acc. Chem. Res. 48, 306–316 (2015).

    Article  CAS  PubMed  Google Scholar 

  30. Stephan, D. W. & Erker, G. Frustrated Lewis pair chemistry: development and perspectives. Angew. Chem. Int. Ed. 54, 6400–6441 (2015).

    Article  CAS  Google Scholar 

  31. Stephan, D. W. The broadening reach of frustrated Lewis pair chemistry. Science 354, aaf7229 (2016).

    Article  PubMed  Google Scholar 

  32. Mahdi, T. & Stephan, D. W. Frustrated Lewis pair catalyzed hydroamination of terminal alkynes. Angew. Chem. Int. Ed. 52, 12418–12421 (2013).

    Article  CAS  Google Scholar 

  33. Mahdi, T. & Stephan, D. W. Stoichiometric and catalytic inter- and intramolecular hydroamination of terminal alkynes by frustrated Lewis pairs. Chem. Eur. J. 21, 11134–11142 (2015).

    Article  CAS  PubMed  Google Scholar 

  34. Ma, G., Song, G. & Li, Z. H. Designing metal-free frustrated Lewis pairs catalyst for the efficient dehydrogenation of ammonia borane. Chem. Eur. J. 24, 13238–13245 (2018).

    Article  CAS  PubMed  Google Scholar 

  35. Zhang, L. et al. Catalytic dehydrogenation of ammonia borane mediated by a Pt(0)/borane frustrated Lewis pair: theoretical design. ChemPhysChem 21, 2573–2578 (2020).

    Article  CAS  PubMed  Google Scholar 

  36. Sarbajna, A., Swamy, V. S. V. S. N. & Gessner, V. H. Phosphorus-ylides: powerful substituents for the stabilization of reactive main group compounds. Chem. Sci. 12, 2016–2024 (2021).

    Article  CAS  Google Scholar 

  37. Krämer, F., Radius, M., Hinz, A., Dilanas, M. E. A. & Breher, F. Accessing cationic α-silylated and α-germylated phosphorus ylides. Chem. Eur. J. 28, e202103974 (2022).

    Article  PubMed  Google Scholar 

  38. Schier, A. & Schmidbaur, H. Derivatives and coordination compounds of triphenylphosphonium cyclopropylide (C6H5)3P=C(CH2)2. Z. Naturforsch. B 37, 1518–1523 (1982).

    Article  Google Scholar 

  39. Dureen, M. A. & Stephan, D. W. Biphenylamide ligand complexes of Li and Al: hemilabile arene donors? J. Chem. Soc. Dalton Trans. (2008).

  40. Swarnakar, A. K. et al. Application of the donor–acceptor concept to intercept low oxidation state group 14 element hydrides using a Wittig reagent as a Lewis base. Inorg. Chem. 53, 8662–8671 (2014).

    Article  CAS  PubMed  Google Scholar 

  41. Korth, K. & Sundermeyer, J. Interaction of t-butyllithium and triphenylmethylenephosphoranes. Tetrahedron Lett. 41, 5461–5464 (2000).

    Article  CAS  Google Scholar 

  42. Radius, M. & Breher, F. α-Borylated phosphorus ylides (α-BCPs): electronic frustration within a C−B π-bond arising from the competition for a lone pair of electrons. Chem. Eur. J. 24, 15744–15749 (2018).

    Article  CAS  PubMed  Google Scholar 

  43. Wiberg, N. Lehrbuch der Anorganischen Chemie. 102nd edn (W. de Gruyter, 2007).

  44. Brook, P. R. & Duke, A. J. Ring-opening reactions of 7,7-dichlorobicyclo[3,2,0]hept-2-en-6-one and its conversion into methyl benzoate with methoxide ion. J. Chem. Soc. C (1971).

  45. Roedig, A., Bonse, G., Ganns, E. M. & Heinze, H. Der einfluss der perchlorsubstitution auf einige ringöffnungsreaktionen des benzocyclobutendions. Tetrahedron 33, 2437–2440 (1977).

    Article  CAS  Google Scholar 

  46. Argouarch, G., Stones, G., Gibson, C. L., Kennedy, A. R. & Sherrington, D. C. Bifurcated, modular syntheses of chiral annulet triazacyclononanes. Org. Biomol. Chem. 1, 4408–4417 (2003).

    Article  CAS  PubMed  Google Scholar 

  47. Zhang, L. et al. Iridium-catalyzed asymmetric hydrogenation of simple ketones with tridentate PNN ligands bearing unsymmetrical vicinal diamines. J. Org. Chem. 88, 2942–2951 (2023).

    Article  CAS  PubMed  Google Scholar 

  48. Kim, J., Kim, H. J. & Chang, S. Synthetic uses of ammonia in transition-metal catalysis. Eur. J. Org. Chem. 2013, 3201–3213 (2013).

    Article  CAS  Google Scholar 

  49. Lawrence, S. A. Amines: Synthesis, Properties and Applications (Cambridge Univ. Press, 2005).

  50. Legnani, L., Bhawal, B. N. & Morandi, B. Recent developments in the direct synthesis of unprotected primary­ amines. Synthesis 49, 776–789 (2017).

    CAS  Google Scholar 

  51. Tshepelevitsh, S. et al. On the basicity of organic bases in different media. Eur. J. Org. Chem. 2019, 6735–6748 (2019).

    Article  CAS  Google Scholar 

  52. Uhl, W., Wagner, J., Fenske, D. & Baum, G. N,N,N′,N′-Tetramethylethylendiamin-di(tert-butyl)aluminium-Kationen—Molekülstruktur des [(Me3C)2Al · TMEDA][(Me3C)2AlBr2] Z. Anorg. Allg. Chem. 612, 25–34 (1992).

    Article  CAS  Google Scholar 

  53. Allen, C. L., Burel, C. & Williams, J. M. J. Cost efficient synthesis of amides from oximes with indium or zinc catalysts. Tetrahedron Lett. 51, 2724–2726 (2010).

    Article  CAS  Google Scholar 

  54. Krämer, F., Paradies, J., Fernández, I. & Breher, F. A crystalline aluminum–carbon-based ambiphile capable of activation and catalytic transfer of ammonia. Preprint at ChemRxiv (2022).

Download references


This work was partly carried out with the support of the Karlsruhe Nano Micro Facility, a Helmholtz research platform at KIT, and we thank D. Fenske, A. Hinz and B. Birenheide for help with X-ray diffraction. We also thank K. Kohnle, A. Mösle, L. Hirsch and A. Hochgesand from the Institute of Organic Chemistry at KIT for performing mass spectral and elemental analysis. R. Nickisch and L. Santos Correa from the Institute of Organic Chemistry at KIT are acknowledged for their help with gel permeation chromatography measurements. The authors acknowledge support by the state of Baden-Württemberg through bwHPC and the German Research Foundation through grant no INST 40/575-1 FUGG (JUSTUS 2 cluster). I.F. is grateful to the Spanish MCIN/AEI/10.13039/501100011033 (grants PID2019-106184GB-I00 and PID2022-139318NB-I00). The authors received no specific funding for this work.

Author information

Authors and Affiliations



F.B. supervised the project. I.F. performed the quantum chemical calculations. J.P. supported the catalytic studies and the van’t Hoff analysis. F.K. conducted all experiments and wrote the manuscript with input from all authors.

Corresponding author

Correspondence to Frank Breher.

Ethics declarations

Competing interests

The authors declare no competing interest.

Peer review

Peer review information

Nature Chemistry thanks Cameron Jones and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–33, discussion and coordinates of the calculated structures.

Supplementary Data 1

Source data for Supplementary Fig. 23a.

Supplementary Data 2

Source data for Supplementary Fig. 23c.

Supplementary Data 3

Crystallographic structure factor data for compound 2; CCDC reference 2180947.

Supplementary Data 4

Crystallographic structure factor data for compound 3; CCDC reference 2180948.

Source data

Source Data Fig. 2

Raw NMR data.

Source Data Fig. 4

Source data for the kinetic studies of the catalytic alkylation of benzylbromide.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Krämer, F., Paradies, J., Fernández, I. et al. A crystalline aluminium–carbon-based ambiphile capable of activation and catalytic transfer of ammonia in non-aqueous media. Nat. Chem. (2023).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing