Skip to main content

Thank you for visiting nature.com. 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.

  • Article
  • Published:

Strongly reducing magnesium(0) complexes

Nature volume 592, pages 717–721 (2021)Cite this article

Subjects

Abstract

A complex of a metal in its zero oxidation state can be considered a stabilized, but highly reactive, form of a single metal atom. Such complexes are common for the more noble transition metals. Although rare examples are known for electronegative late-main-group p-block metals or semimetals1,2,3,4,5,6, it is a challenge to isolate early-main-group s-block metals in their zero oxidation state7,8,9,10,11. This is directly related to their very low electronegativity and strong tendency to oxidize. Here we present examples of zero-oxidation-state magnesium (that is, magnesium(0)) complexes that are stabilized by superbulky, monoanionic, β-diketiminate ligands. Whereas the reactivity of an organomagnesium compound is typically defined by the nucleophilicity of its organic groups and the electrophilicity of Mg2+ cations, the Mg0 complexes reported here feature electron-rich Mg centres that are nucleophilic and strongly reducing. The latter property is exemplified by the ability to reduce Na+ to Na0. We also present a complex with a linear Mg3 core that formally could be described as a MgI–Mg0–MgI unit. Such multinuclear mixed-valence Mgn clusters are discussed as fleeting intermediates during the early stages of Grignard reagent formation. Their remarkably strong reducing power implies a rich reactivity and application as specialized reducing agents.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Fig. 1: Low-valent complexes of main group metals and semimetals.
Fig. 2: Synthesis and reactivity of β-diketiminate Mg0 complexes.
Fig. 3: Molecular structures and Laplacian distribution of the electron density for the Mg0 complexes.
Fig. 4: Calculated energy profiles for stepwise loss of Mg0 in trinuclear Mg–Mg–Mg complexes.

Similar content being viewed by others

Data availability

X-ray data are available free of charge from the Cambridge Crystallographic Data Centre under references CCDC 2045616 (1), 2045617 (2), 2045618 (3), 2045619 (4) and 2045620 (5). Spectroscopic data that support the findings of this study as well as complementary crystallographic and computational details are included in Supplementary Information. Raw data are available from the corresponding author on reasonable request.

References

  1. Wang, Y. et al. A stable silicon(0) compound with a Si=Si double bond. Science 321, 1069–1071 (2008).

    Article  ADS  CAS  PubMed  Google Scholar 

  2. Sidiropoulos, A., Jones, C., Stasch, A., Klein, S. & Frenking, G. N-Heterocyclic carbene stabilized digermanium(0). Angew. Chem. Int. Edn 48, 9701–9704 (2009).

    Article  CAS  Google Scholar 

  3. Braunschweig, H. et al. Ambient-temperature isolation of a compound with a boron-boron triple bond. Science 336, 1420–1422 (2012).

    Article  ADS  CAS  PubMed  Google Scholar 

  4. Jones, C., Sidiropoulos, A., Holzmann, N., Frenking, G. & Stasch, A. An N-heterocyclic carbene adduct of diatomic tin, :Sn=Sn:. Chem. Commun. 48, 9855–9857 (2012).

    Article  CAS  Google Scholar 

  5. Mondal, K. C. et al. A stable singlet biradicaloid siladicarbene: (L:)2Si. Angew. Chem. Int. Edn 52, 2963–2967 (2013).

    Article  CAS  Google Scholar 

  6. Li, Y. et al. Acyclic germylones: congeners of allenes with a central germanium atom. J. Am. Chem. Soc. 135, 12422–12428 (2013).

    Article  CAS  PubMed  Google Scholar 

  7. Glaunsinger, W. S. et al. Structure and molecular motions in alkaline earth hexammines. Nature 271, 414–417 (1978).

    Article  ADS  CAS  PubMed  Google Scholar 

  8. Wu, X. et al. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science 361, 912–916 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  9. Wang, Q. et al. Transition-metal chemistry of alkaline-earth elements: the trisbenzene complexes M(Bz)3 (M=Sr, Ba). Angew. Chem. Int. Edn 58, 17365–17374 (2019).

    Article  CAS  Google Scholar 

  10. Arrowsmith, M. et al. Neutral zero-valent s-block complexes with strong multiple bonding. Nat. Chem. 8, 890–894 (2016).

    Article  CAS  Google Scholar 

  11. Couchman, S. A., Holzmann, N., Frenking, G., Wilson, D. J. D. & Dutton, J. L. Beryllium chemistry the safe way: a theoretical evaluation of low oxidation state beryllium compounds. Dalton Trans. 42, 11375–11384 (2013).

    Article  CAS  PubMed  Google Scholar 

  12. Green, S. P., Jones, C. & Stasch, A. Stable magnesium(I) compounds with Mg–Mg bonds. Science 318, 1754–1757 (2007).

    Article  ADS  CAS  PubMed  Google Scholar 

  13. Jones, C. Dimeric magnesium(I) β-diketiminates: a new class of quasi-universal reducing agent. Nat. Rev. Chem. 1, 0059 (2017).

    Article  CAS  Google Scholar 

  14. Jones, C. Open questions in low oxidation state group 2 chemistry. Commun. Chem. 3, 159 (2020).

    Article  Google Scholar 

  15. Gentner, T. X. et al. Low valent magnesium chemistry with a super bulky β‐diketiminate ligand. Angew. Chem. Int. Edn 58, 607–611 (2019).

    Article  CAS  Google Scholar 

  16. Jones, D. D. L., Douair, I., Maron, L. & Jones, C. Photochemically activated dimagnesium(I) compounds: reagents for the reduction and selective C–H bond activation of inert arenes. Angew. Chem. Int. Edn 60, 7087–7092 (2021).

  17. Rösch, B. et al. Mg-Mg bond polarization induced by a superbulky β-diketiminate ligand. Chem. Commun. 56, 11402–11405 (2020).

    Article  Google Scholar 

  18. Hicks, J., Juckel, M., Paparo, A., Dange, D. & Jones, C. Multigram syntheses of magnesium(I) compounds using alkali metal halide supported alkali metals as dispersible reducing agents. Organometallics 37, 4810–4813 (2018).

    Article  CAS  Google Scholar 

  19. Cui, C. et al. Synthesis and structure of a monomeric aluminum(I) compound [{HC(CMeNAr)2}Al] (Ar=2,6-iPr2C6H3): a stable aluminum analogue of a carbene. Angew. Chem. Int. Edn 39, 4274–4276 (2000).

    Article  CAS  Google Scholar 

  20. Hicks, J., Vasko, P., Goicoechea, J. M. & Aldridge, S. Synthesis, structure and reaction chemistry of a nucleophilic aluminyl anion. Nature 557, 92–95 (2018); correction 560, E24 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  21. Dye, J. L., Ceraso, J. M., Lok Tak, M., Barnett, B. L. & Tehan, F. J. Crystalline salt of the sodium anion (Na–). J. Am. Chem. Soc. 96, 608–609 (1974).

    Article  CAS  Google Scholar 

  22. Camp, C. & Arnold, J. On the non-innocence of “NacNacs”: ligand-based reactivity in β-diketiminate supported coordination compounds. Dalton Trans. 45, 14462–14498 (2016).

    Article  CAS  PubMed  Google Scholar 

  23. Slater, J. C. Atomic radii in crystals. J. Chem. Phys. 41, 3199–3204 (1964).

    Article  ADS  CAS  Google Scholar 

  24. Lambert, C. & von Ragué Schleyer, P. Are polar organometallic compounds “carbanions”? The gegenion effect on structure and energies of alkali-metal compounds. Angew. Chem. Int. Edn Engl. 33, 1129–1140 (1994).

    Article  Google Scholar 

  25. Cao, W. L., Gatti, C., MacDougall, P. J. & Bader, R. F. W. On the presence of non-nuclear attractors in the charge distributions of Li and Na clusters. Chem. Phys. Lett. 141, 380–385 (1987).

    Article  ADS  CAS  Google Scholar 

  26. Gentner, T. X. & Mulvey, R. E. Alkali metal mediation: diversity of applications in main group organometallic chemistry. Angew. Chem. Int. Edn 59, 2–18 (2020).

    Google Scholar 

  27. Arrowsmith, M. et al. Mononuclear three-coordinate magnesium complexes of a highly sterically encumbered β-diketiminate ligand. Inorg. Chem. 53, 10543–10552 (2014).

    Article  CAS  PubMed  Google Scholar 

  28. Bakewell, C., White, A. J. P. & Crimmin, M. R. Addition of carbon-fluorine bonds to a Mg(I)-Mg(I) bond: an equivalent of Grignard formation in solution. J. Am. Chem. Soc. 138, 12763–12766 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Hicks, J., Underhill, E. J., Kefalidis, C. E., Maron, L. & Jones, C. A mixed-valence tri-zinc complex, [LZnZnZnL] (L=bulky amide), bearing a linear chain of two-coordinate zinc atoms. Angew. Chem. Int. Edn 54, 10000–10004 (2015).

    Article  CAS  Google Scholar 

  30. Bakewell, C., Ward, B. J., White, A. J. P. & Crimmin, M. R. A combined experimental and computational study on the reaction of fluoroarenes with Mg-Mg, Mg-Zn, Mg-Al and Al-Zn bonds. Chem. Sci. 9, 2348–2356 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Platts, J. A., Overgaard, J., Jones, C., Iversen, B. B. & Stasch, A. First experimental characterization of a non-nuclear attractor in a dimeric magnesium(I) compound. J. Phys. Chem. A 115, 194–200 (2011).

    Article  CAS  PubMed  Google Scholar 

  32. Garst, G. F. & Ungvary, F. in Grignard Reagents: New Developments (ed. Richey, H.) 185–276 (Wiley, 2000).

  33. Tjurina, L. A. et al. Synthesis of cluster alkyl and aryl Grignard reagents in solution. Organometallics 23, 1349–1351 (2004).

    Article  CAS  Google Scholar 

  34. Imizu, Y. & Klabunde, K. J. Metal cluster vs. atom reactivities: magnesium cluster Grignard reagents. Inorg. Chem. 23, 3602–3605 (1984).

    Article  CAS  Google Scholar 

  35. Köhn, A., Weigend, F. & Ahlrichs, R. Theoretical study on clusters of magnesium. Phys. Chem. Chem. Phys. 3, 711–719 (2001).

    Article  Google Scholar 

  36. Eriksson, L. A. Accurate density functional theory study of cationic magnesium clusters and Mg+-rare gas interactions. J. Chem. Phys. 103, 1050–1056 (1995).

    Article  ADS  CAS  Google Scholar 

  37. Kruczyński, T., Henke, F., Neumaier, M., Bowen, K. H. & Schnöckel, H. Many Mg-Mg bonds form the core of the Mg16Cp*8Br4K cluster anion: the key to a reassessment of the Grignard reagent (GR) formation process? Chem. Sci. 7, 1543–1547 (2016).

    Article  PubMed  Google Scholar 

  38. Velazquez, A., Fernández, I., Frenking, G. & Merino, G. Multimetallocenes. A theoretical study. Organometallics 26, 4731–4736 (2007).

    Article  CAS  Google Scholar 

  39. Chase, M. W. Jr NIST-JANAF Thermochemical Tables Part 2, 4th edn (Monograph No. 9, J. Phys. Chem. Ref. Data, American Institution of Physics, 1998).

  40. Clegg, W. et al. Synthesis and structures of [(trimethylsilyl)methyl]sodium and ‐potassium with bi‐ and tridentate N‐donor ligands. Eur. J. Inorg. Chem. 721–726 (2011).

  41. Rigaku Oxford Diffraction. CrysAlisPro Software system, version 1.171.40.67a (Rigaku Corporation, 2018).

  42. Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. OLEX2: a complete structure solution, refinement and analysis program. J. Appl. Crystallogr. 42, 339–341 (2009).

    Article  CAS  Google Scholar 

  43. Sheldrick, G. M. SHELXT — Integrated space-group and crystal-structure determination. Acta Crystallogr. A 71, 3–8 (2015).

    Article  MATH  Google Scholar 

  44. Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr. C 71, 3–8 (2015).

    Article  MATH  Google Scholar 

  45. Frisch, M. J. et al. Gaussian 16 Rev. A.03 (Gaussian, Inc., 2016).

  46. Becke, A. D. A new mixing of Hartree–Fock and local density‐functional theories. J. Chem. Phys. 98, 1372–1377 (1993).

    Article  ADS  CAS  Google Scholar 

  47. Perdew, J. P. Electronic Structure of Solids (Akademie, 1991).

  48. Weigend, F. & Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy. Phys. Chem. Chem. Phys. 7, 3297–3305 (2005).

    Article  CAS  PubMed  Google Scholar 

  49. Grimme, S., Antony, J., Ehrlich, S. & Krieg, H. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 132, 154104 (2010).

    Article  ADS  PubMed  Google Scholar 

  50. Reed, A. E., Weinstock, R. B. & Weinhold, F. Natural population analysis. J. Chem. Phys. 83, 735–746 (1985).

    Article  ADS  CAS  Google Scholar 

  51. Bader, R. F. W. A quantum theory of molecular structure and its applications. Chem. Rev. 91, 893–928 (1991).

    Article  CAS  Google Scholar 

  52. Keith, T. A. AIMAll Version 17.01.25 (TK Gristmill Software, 2017).

Download references

Acknowledgements

We thank A. Roth (FAU) and the Kolbe Microanalytical Laboratory (Mülheim/Ruhr) for elemental analysis. This work was generously supported by the University of Erlangen-Nürnberg.

Author information

Authors and Affiliations

  1. Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany

    B. Rösch, T. X. Gentner, J. Eyselein, J. Langer, H. Elsen & S. Harder

Authors
  1. B. Rösch
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. T. X. Gentner
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. J. Eyselein
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. J. Langer
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. H. Elsen
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. S. Harder
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

B.R.: conceptualization, investigation, validation, formal analysis (that is, analyses of raw data from spectroscopy, X-ray diffraction or computational methods), writing of original draft and visualization. T.X.G.: investigation, validation and formal analysis. J.E.: formal analysis. J.L.: formal analysis. H.E.: formal analysis. S.H.: conceptualization, writing of original draft, review and editing, visualization, supervision and project administration.

Corresponding author

Correspondence to S. Harder.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Jason Dutton and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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

Supplementary information

Supplementary Information

This file contains: Spectroscopic characterization (including Supplementary Figs. 1 to 41); Crystal structure determination (including Supplementary Figs. 42 to 46 and Supplementary Tables 1 to 5); Comparison of chemical shifts and bond distances for (BDI*)Mg complexes (including Supplementary Table 6); Computational details (including Supplementary Figs. 47 to 57 and Supplementary Tables 7-15); Arguments in favor for the correct metal assignment in {[(BDI*)Mg−][Na+]}2 (1); and Supplementary References.

Peer Review File

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Rösch, B., Gentner, T.X., Eyselein, J. et al. Strongly reducing magnesium(0) complexes. Nature 592, 717–721 (2021). https://doi.org/10.1038/s41586-021-03401-w

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-021-03401-w

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

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