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Isolation, characterization and reactivity of three-coordinate phosphorus dications isoelectronic to alanes and silylium cations

Nature Chemistry volume 11, pages 1139–1143 (2019)Cite this article

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Abstract

Three-coordinate main group Lewis acids are exceedingly important reagents in chemical synthesis. In contrast to the well-established chemistries of neutral group 13 and cationic group 14 species, isoelectronic group 15 element dications are unknown. In this work, we use stabilizing N-heterocyclic imine substituents to isolate and characterize phosphorandiylium dications ([R3P]2+) and show that the electrophilicity at the phosphorus atoms is controlled by the π-electron-donating ability of these subtituents. Structural, spectroscopic and theoretical results reveal that the phosphorus dications adopt a perfectly trigonal-planar geometry with the electron-deficient phosphorus centres being well separated from the borate anions. The reactivity of the dications reveal their exceptional Lewis acidity at phosphorus; the adjacent nitrogen atoms, however, are weakly basic, resulting in transformations such as chloride ion abstraction from Me3SiCl and the selective monodefluorination of trifluoromethyl groups.

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Fig. 1: Synthesis and solid-state structure of phosphorandiylium ion [2]2+.
Fig. 2: A theoretical and experimental study of the electronic nature of [2]2+.
Fig. 3: Synthesis of the phosphorandiylium salt [12][B(C6F5)4]2.

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Data availability

Spectral and purity data are available for all new compounds, along with original NMR, mass spectrometry and density functional theory data. The single-crystal X-ray crystallographic data for [2][BArF24]2 has been deposited at the Cambridge Crystallographic Data Centre, under deposition nos. CCDC 1905044. Copies of the data can be obtained free of charge from https://www.ccdc.cam.ac.uk/structures/. All other data supporting the findings of this study are available within the Article and its Supplementary Information, or from the corresponding author on reasonable request.

References

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

    PubMed  Google Scholar 

  2. Greb, L. Lewis superacids: classifications, candidates, and applications. Chem. Eur. J. 24, 17881–17896 (2018).

    CAS  PubMed  Google Scholar 

  3. Piers, W. E. & Chivers, T. Pentafluorophenylboranes: from obscurity to applications. Chem. Soc. Rev. 26, 345–354 (1997).

    CAS  Google Scholar 

  4. Böhrer, H., Trapp, N., Himmel, D., Schleep, M. & Krossing, I. From unsuccessful H2-activation with FLPs containing B(Ohfip)3 to a systematic evaluation of the Lewis acidity of 33 Lewis acids based on fluoride, chloride, hydride and methyl ion affinities. Dalton Trans. 44, 7489–7499 (2015).

    PubMed  Google Scholar 

  5. Pohlmann, J. L. W. & Brinckmann, F. E. Preparation and characterization of group III A derivatives. Z. Naturforsch. B 20, 5–11 (1965).

    Google Scholar 

  6. Chen, E. Y.-X. Tris(pentafluorophenyl)alane. Encycl. Reag. Org. Syn. https://doi.org/10.1002/047084289X.rn01382 (2012).

  7. Müller, L. O. et al. Simple access to the non-oxidizing Lewis superacid PhF→Al(ORF)3 (RF=C(CF3)3. Angew. Chem. Int. Ed. 47, 7659–7663 (2008)..

  8. Kim, K.-C. K. et al. Crystallographic evidence for a free silylium ion. Science 297, 825–827 (2002).

    CAS  PubMed  Google Scholar 

  9. Gaspar, P. P. R3Si+—free at last. Science 297, 785–786 (2002).

    PubMed  Google Scholar 

  10. Reed, C. A. The silylium ion problem, R3Si+. Bridging organic and inorganic chemistry. Acc. Chem. Res. 31, 325–332 (1998).

    CAS  Google Scholar 

  11. Klare, H. F. T. & Oestreich, M. Silylium ions in catalysis. Dalton Trans. 39, 9176–9184 (2010).

    CAS  PubMed  Google Scholar 

  12. Bähr, S. & Oestreich, M. Electrophilic aromatic substitution with silicon electrophiles: catalytic friedel-crafts C–H silylation. Angew. Chem. Int. Ed. 56, 52–59 (2017).

    Google Scholar 

  13. Douvris, C. & Ozerov, O. V. Hydrodefluorination of perfluoroalkyl groups using silylium–carborane catalysts. Science 321, 1188–1190 (2008).

    CAS  PubMed  Google Scholar 

  14. Douvris, C., Nagaraja, C. M., Chen, C.-H., Foxman, B. M. & Ozerov, O. V. Hydrodefluorination and other hydrodehalogenation of aliphatic carbon–halogen bonds using silylium catalysis. J. Am. Chem. Soc. 132, 4946–4953 (2010).

    CAS  PubMed  Google Scholar 

  15. Scott, V. J., Celenligil-Cetin, R. & Ozerov, O. V. Room-temperature catalytic hydrodefluorination of C(sp 3)–F bonds. J. Am. Chem. Soc. 127, 2852–2853 (2005).

    CAS  PubMed  Google Scholar 

  16. Allemann, O., Duttwyler, S., Romanato, P., Baldridge, K. K. & Siegel, J. S. Proton-catalyzed, silane-fueled Friedel–Crafts coupling of fluoroarenes. Science 332, 574–577 (2011).

    CAS  PubMed  Google Scholar 

  17. Shao, B., Bagdasarian, A. L., Popov, S. & Nelson, H. M. Arylation ofhydrocarbons enabled by organosilicon reagents and weakly coordinating anions. Science 355, 1403–1407 (2017).

    CAS  PubMed  Google Scholar 

  18. Popov, S. et al. Teaching an old carbocation new tricks: intermolecular C–H insertion reactions of vinyl cations. Science 361, 381–387 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  19. Yogendra, S. et al. Carbodiphosphorane mediated synthesis of a triflyloxyphosphonium dication and its reactivity towards nucleophiles. Chem. Commun. 53, 2954–2957 (2017).

    CAS  Google Scholar 

  20. Holthausen, M. H., Mehta, M. & Stephan, D. W. The highly Lewis acidic dicationic phosphonium salt: [(SIMes)PFPh2][B(C6F5)4]2. Angew. Chem. Int. Ed. 53, 6538–6541 (2014).

    CAS  Google Scholar 

  21. Weigand, J. J., Riegel, S. D., Burford, N. & Decken, A. Prototypical phosphorus analogues of ethane. General and versatile synthetic approaches to hexaalkylated P–P diphosphonium cations. J. Am. Chem. Soc. 129, 7969–7976 (2007).

    CAS  PubMed  Google Scholar 

  22. Weigand, J. J., Burford, N., Decken, A. & Schulz, A. Preparation and characterization of a ligand-stabilized trimethylphosphane dication. Eur. J. Inorg. Chem. https://doi.org/10.1002/ejic.200700826 (2007).

  23. Robertson, A. P. M. et al. Establishing the coordination chemistry of antimony(v) cations: systematic assessment of Ph4Sb(OTf) and Ph3Sb(OTf)2 as Lewis acceptors. Chem. Eur. J. 21, 7902–7913 (2015).

    CAS  PubMed  Google Scholar 

  24. Donath, M., Bodensteiner, M. & Weigand, J. J. Versatile reagent Ph3As(OTf)2: one-pot synthesis of P7(AsPh3)3OTf3 from PCl3. Chem. Eur. J. 20, 17306–17310 (2014).

    CAS  PubMed  Google Scholar 

  25. Robertson, A. P. M., Burford, N., McDonald, R. & Ferguson, M. J. Coordination complexes of Ph3Sb2+ and Ph3Bi2+: beyond pnictonium cations. Angew. Chem. Int. Ed. 53, 3480–3483 (2014).

    CAS  Google Scholar 

  26. Klare, H. F. T. Catalytic C–H Arylation of Unactivated C–H Bonds by Silylium Ion-Promoted C(sp 2)–F Bond Activation. ACS Catal. 7, 6999–7002 (2017).

    CAS  Google Scholar 

  27. Piers, W. E., Bourke, S. C. & Conroy, K. D. Borinium, borenium, and boronium ions: synthesis, reactivity, and applications. Angew. Chem. Int. Ed. 44, 5016–5036 (2005).

    CAS  Google Scholar 

  28. Dagorne, S. & Wehmschulte, R. Recent developments on the use of group 13 metal complexes in catalysis. ChemCatChem 10, 2509–2520 (2018).

    CAS  Google Scholar 

  29. Vries, T. S., de, Prokofjevs, A. & Vedejs, E. Cationic tricoordinate boron intermediates: borenium chemistry from the organic perspective. Chem. Rev. 112, 4246–4282 (2012).

    PubMed  PubMed Central  Google Scholar 

  30. Bayne, J. M. & Stephan, D. W. Phosphorus Lewis acids. Emerging reactivity and applications in catalysis. Chem. Soc. Rev. 45, 765–774 (2016).

    CAS  PubMed  Google Scholar 

  31. Ochiai, T., Franz, D. & Inoue, S. Applications of N-heterocyclic imines in main group chemistry. Chem. Soc. Rev. 45, 6327–6344 (2016).

    CAS  PubMed  Google Scholar 

  32. Mehlmann, P., Mück-Lichtenfeld, C., Tan, T. T. Y. & Dielmann, F. Tris(imidazolin-2-ylidenamino)phosphine. A crystalline phosphorus(iii) superbase that splits carbon dioxide. Chem. Eur. J. 23, 5929–5933 (2017).

    CAS  PubMed  Google Scholar 

  33. Wünsche, M. A. et al. Imidazolin-2-ylidenaminophosphines as highly electron-rich ligands for transition-metal catalysts. Angew. Chem. Int. Ed. 54, 11857–11860 (2015).

    Google Scholar 

  34. Buß, F., Mehlmann, P., Mück-Lichtenfeld, C., Bergander, K. & Dielmann, F. Reversible carbon dioxide binding by simple lewis base adducts with electron-rich phosphines. J. Am. Chem. Soc. 138, 1840–1843 (2016).

    PubMed  Google Scholar 

  35. Buß, F., Mück-Lichtenfeld, C., Mehlmann, P. & Dielmann, F. Nucleophilic activation of sulfur hexafluoride. metal-free, selective degradation by phosphines. Angew. Chem. Int. Ed. 130, 5045–5049 (2018).

    Google Scholar 

  36. Kira, M., Hino, T. & Sakurai, H. Chemistry of organosilicon compounds. 292. An NMR study of the formation of silyloxonium ions by using tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as counteranion. J. Am. Chem. Soc. 114, 6697–6700 (1992).

    CAS  Google Scholar 

  37. Christe, K. O. et al. On a quantitative scale for Lewis acidity and recent progress in polynitrogen chemistry. J. Fluor. Chem. 101, 151–153 (2000).

    CAS  Google Scholar 

  38. Petersen, T. O., Simone, D. & Krossing, I. From ion-like ethylzinc aluminates to [EtZn(arene)2]+ [Al(ORF)4]– salts. Chem. Eur. J. 22, 15847–15855 (2016).

    CAS  PubMed  Google Scholar 

  39. Himmel, D., Scherer, H., Kratzert, D. & Krossing, I. Synthesis and characterization of Cp*Be–F–Al(ORF)3. Z. Anorg. Allg. Chem. 641, 655–659 (2015).

    CAS  Google Scholar 

  40. Couchman, S. A., Wilson, D. J. D. & Dutton, J. L. Is the perfluorinated trityl cation worth a revisit? A theoretical study on the lewis acidities and stabilities of highly halogenated trityl derivatives. Eur. J. Org. Chem. 18, 3902–3908 (2014).

    Google Scholar 

  41. Gutmann, V. Solvent effects on the reactivity of organometallic compounds. Coord. Chem. Rev. 18, 225–255 (1976).

    CAS  Google Scholar 

  42. Beckett, M. A., Brassington, D. S., Coles, S. J. & Hursthouse, M. B. Lewis acidity of tris(pentafluorophenyl)borane: crystal and molecular structure B(C6F5)3–OPEt3. Inorg. Chem. Commun. 3, 530–533 (2000).

    CAS  Google Scholar 

  43. Martens, A., Petersen, O., Scherer, H., Riddlestone, I. & Krossing, I. From a (pseudo) aluminum sesquihalide Al2(Et)3(ORF)3 to Me3Si–Cl–Al(ORF)3 (RF=C(CF3)3. Organometallics 37, 706–711 (2018)..

  44. Yoshida, S., Shimomori, K., Kim, Y. & Hosoya, T. Single C–F bond cleavage of trifluoromethylarenes with an ortho-silyl group. Angew. Chem. Int. Ed. 55, 10406–10409 (2016).

    CAS  Google Scholar 

  45. Mallov, I., Ruddy, A. J., Zhu, H., Grimme, S. & Stephan, D. W. C.-F. Bond activation by silylium cation/phosphine frustrated Lewis pairs: mono-hydrodefluorination of PhCF3, PhCF2H and Ph2CF2. Chem. Eur. J. 23, 17692–17696 (2017).

    CAS  PubMed  Google Scholar 

  46. Kuhn, N. & Kratz, T. Synthesis of imidazol-2-ylidenes by reduction of imidazole-2(3H)-thiones. Synthesis 6, 561–562 (1993).

    Google Scholar 

  47. Tamm, M. et al. Structural and theoretical investigation of 2-iminoimidazolines—carbene analogues of iminophosphoranes. Org.Biomol. Chem. 5, 523–530 (2007).

    CAS  PubMed  Google Scholar 

  48. Weber, L. et al. Electrochemical and spectroelectrochemical studies of C-benzodiazaborolyl-ortho-carboranes. Dalton Trans. 42, 2266–2281 (2013).

    CAS  PubMed  Google Scholar 

  49. Yakelis, N. A. & Bergman, R. G. Safe preparation and purification of sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF24): reliable and sensitive analysis of water in solutions of fluorinated tetraarylborates. Organometallics 24, 3579–3581 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

The authors gratefully acknowledge financial support from the DFG (Emmy Noether programme grant no.: DI 2054/1-1, SFB 858). We thank F. E. Hahn for his generous support and C. Mück-Lichtenfeld for his help with computations. Correspondence and requests for materials should be addressed to F.D.

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  1. Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Munster, Germany

    Paul Mehlmann, Tim Witteler, Lukas F. B. Wilm & Fabian Dielmann

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Contributions

F.D. and P.M. conceived the research. P.M. and L.W. carried out the synthetic experiments and analysed the experimental data. T.W. performed the computational investigations. F.D. performed the X-ray single-crystal structure analysis, directed the investigation and wrote the manuscript with suggestions from P.M.

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Correspondence to Fabian Dielmann.

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Supplementary information

Supplementary Information

Experimental details, synthetic procedures, compound characterization data including spectral and purity data for all new compounds; NMR spectra; single-crystal X-ray crystallographic data; computational details along with fluoride ion affinities of model compounds and Cartesian coordinates of computational structures.

[2][BArF24]2.cif

Crystallographic data for compound [2][BArF24]2. CCDC reference 1905044

[2][BArF24]2_structfact.fcf

Structure factors file for compound [2][BArF24]2. CCDC reference 1905044

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Mehlmann, P., Witteler, T., Wilm, L.F.B. et al. Isolation, characterization and reactivity of three-coordinate phosphorus dications isoelectronic to alanes and silylium cations. Nat. Chem. 11, 1139–1143 (2019). https://doi.org/10.1038/s41557-019-0348-0

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