Abstract
The inimitable electronic structures of the lanthanide (Ln) ions are key to advanced materials and technologies involving these elements. The trivalent ions are ubiquitous and are used much more widely than the divalent and tetravalent analogues, which possess vastly different optical and magnetic properties. Hence, alteration of the valence electron count by external stimuli can lead to dramatic changes in materials properties. Compounds exhibiting a temperature-induced complete Ln(III) ⇄ Ln(II) switch, referred to as a valence tautomeric (VT) transition, are rare. Here we present an abrupt and hysteretic VT transition in a lanthanide-based coordination polymer, SmI2(pyrazine)3, driven by the interconversion of Sm(II)–pyrazine(0) and Sm(III)–pyrazine(·−) redox pairs. Alloying SmI2(pyrazine)3 with Yb(II) yields isomorphous Sm1–xYbxI2(pyrazine)3 solid solutions with VT transition critical temperatures ranging widely from 200 K to ∼50 K at ambient pressure. These findings demonstrate a simple strategy to realize thermally switchable magnetic materials with chemically tunable transition temperatures.
Similar content being viewed by others
Data availability
All data are available in the main text or 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 CCDC 2285789 (SmI2(pyz)3 at 230 K), 2285788 (SmI2(pyz)3 at 170 K), 2300988 (YbI2(pyz)3 at 230 K), 2300987 (YbI2(pyz)3 at 170 K) and 2285790 (YbI2(pyz)3 at 120 K). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Source data are provided with this paper.
References
Bünzli, J.-C. G. in The Lanthanides and Actinides (eds Liddle, S. T., Mills, D. P. & Natrajan, L. S.) 633–685 (World Scientific, 2022).
Ramanathan, A. et al. Chemical design of electronic and magnetic energy scales of tetravalent praseodymium materials. Nat. Commun. 14, 3134 (2023).
Münzfeld, L. et al. Synthesis and properties of cyclic sandwich compounds. Nature https://doi.org/10.1038/s41586-023-06192-4 (2023).
Gould, C. A. et al. Ultrahard magnetism from mixed-valence dilanthanide complexes with metal–metal bonding. Science 375, 198–202 (2022).
Sato, O. Dynamic molecular crystals with switchable physical properties. Nat. Chem. 8, 644–656 (2016).
Tricoire, M., Mahieu, N., Simler, T. & Nocton, G. Intermediate valence states in lanthanide compounds. Chem. Eur. J. 27, 6860–6879 (2021).
Chen, B. et al. Novel valence transition in elemental metal europium around 80 GPa. Phys. Rev. Lett. 129, 016401 (2022).
Song, J., Fabbris, G., Bi, W., Haskel, D. & Schilling, J. S. Pressure-induced superconductivity in elemental ytterbium metal. Phys. Rev. Lett. 121, 037004 (2018).
Jayaraman, A., Narayanamurti, V., Bucher, E. & Maines, R. G. Continuous and discontinuous semiconductor–metal transition in samarium monochalcogenides under pressure. Phys. Rev. Lett. 25, 1430 (1970).
Stevens, K. W. H. Fluctuating valence in SmS. J. Phys. C 9, 1417–1429 (1976).
Sousanis, A., Smet, P. F. & Poelman, D. Samarium monosulfide (SmS): reviewing properties and applications. Materials 10, 953 (2017).
Haga, Y. et al. Pressure-induced magnetic phase transition in gold-phase SmS. Phys. Rev. B 70, 220506(R) (2004).
Gilbert Corder, S. N. et al. Near-field spectroscopic investigation of dual-band heavy fermion metamaterials. Nat. Commun. 8, 2262 (2017).
Stern, A., Dzero, M., Galitski, V. M., Fisk, Z. & Xia, J. Surface-dominated conduction up to 240 K in the Kondo insulator SmB6 under strain. Nat. Mater. 16, 708–712 (2017).
Robinson, P. J. et al. Dynamical bonding driving mixed valency in a metal boride. Angew. Chem. Int. Ed. 59, 10996–11002 (2020).
Radzieowski, M. et al. Abrupt europium valence change in Eu2Pt6Al15 around 45 K. J. Am. Chem. Soc. 140, 8950–8957 (2018).
Arvanitidis, J., Papagelis, K., Margadonna, S., Prassides, K. & Fitch, A. N. Temperature-induced valence transition and associated lattice collapse in samarium fulleride. Nature 425, 599–602 (2003).
Buchanan, R. M. & Pierpont, C. G. Tautomeric catecholate-semiquinone interconversion via metal-ligand electron transfer. Structural, spectral, and magnetic properties of (3,5-di-tert-butylcatecholato)-(3,5-di-tert-butylsemiquinone)-(bipyridyl)cobalt(III), a complex containing mixed-valence organic ligands. J. Am. Chem. Soc. 102, 4951–4957 (1980).
Hendrickson, D. N. & Pierpont, C. G. Valence tautomeric transition metal complexes. Top. Curr. Chem. 234, 63–95 (2004).
Gransbury, G. K. & Boskovic, C. in Encyclopedia of Inorganic and Bioinorganic Chemistry (ed. Scott, R. A.) 1–24 (John Wiley, 2021).
Fedushkin, I. L. et al. Genuine redox isomerism in a rare-earth-metal complex. Angew. Chem. Int. Ed. 51, 10584–10587 (2012).
Fedushkin, I. L., Maslova, O. V., Baranov, E. V. & Shavyrin, A. S. Redox isomerism in the lanthanide complex [(dpp-bian)Yb(DME)(μ-Br)]2 (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene. Inorg. Chem. 48, 2355–2357 (2009).
Pedersen, K. S. et al. Formation of the layered conductive magnet CrCl2(pyrazine)2 through redox-active coordination chemistry. Nat. Chem. 10, 1056–1061 (2018).
Perlepe, P. et al. Metal–organic magnets with large coercivity and ordering temperatures up to 242 °C. Science 370, 587–592 (2020).
Huang, Y. et al. Chemical tuning meets 2D molecular magnets. Adv. Mater. 35, 2208919 (2023).
Huang, Y. et al. Pressure-controlled magnetism in 2D molecular layers. Nat. Commun. 14, 3186 (2023).
Perlepe, P. et al. From an antiferromagnetic insulator to a strongly correlated metal in square-lattice MCl2(pyrazine)2 coordination solids. Nat. Commun. 13, 5766 (2022).
Voigt, L., Kubus, M. & Pedersen, K. S. Chemical engineering of quasicrystal approximants in lanthanide-based coordination solids. Nat. Commun. 11, 4705 (2020).
Chen, H. et al. Magnetic Archimedean tessellations in metal–organic frameworks. J. Am. Chem. Soc. 143, 14041–14045 (2021).
Chen, H. et al. Towards frustration in Eu(II) Archimedean tessellations. Chem. Commun. 59, 1609–1612 (2023).
Bratsch, S. G. Standard electrode potentials and temperature coefficients in water at 298.15 K. J. Phys. Chem. Ref. Data 18, 1–21 (1989).
Szostak, M., Fazakerley, N. J., Parmar, D. & Procter, D. J. Cross-coupling reactions using samarium(II) iodide. Chem. Rev. 114, 5959–6039 (2014).
Kubus, M., Voigt, L. & Pedersen, K. S. Pentagonal-bipyramidal acetonitrile complexes of the lanthanide(II) iodides. Inorg. Chem. Commun. 114, 107819 (2020).
Kaim, W. The versatile chemistry of 1,4-diazines: organic, inorganic and biochemical aspects. Angew. Chem. Int. Ed. 22, 171–190 (1983).
Fieser, M. E. et al. Evaluating the electronic structure of formal LnII ions in LnII(C5H4SiMe3)31– using XANES spectroscopy and DFT calculations. Chem. Sci. 8, 6076–6091 (2017).
Deen, P. P. et al. Structural and electronic transitions in the low-temperature, high-pressure phase of SmS. Phys. Rev. B 71, 245118 (2005).
Zasimov, P. et al. HERFD-XANES and RIXS study on the electronic structure of trivalent lanthanides across a series of isostructural compounds. Inorg. Chem. 61, 1817–1830 (2022).
Goodwin, C. A. P. et al. Heteroleptic samarium(III) halide complexes probed by fluorescence-detected L3-edge X-ray absorption spectroscopy. Dalton Trans. 47, 10613–10625 (2018).
Fatila, E. M. et al. Ferromagnetic ordering of –[Sm(III)-radical]n– coordination polymers. Chem. Commun. 52, 5414–5417 (2016).
Bonner, J. C. & Fisher, M. E. Linear magnetic chains with anisotropic coupling. Phys. Rev. 135, A640 (1964).
Pan, Y.-Z. et al. A slowly magnetic relaxing SmIII monomer with a D5h equatorial compressed ligand field. Inorg. Chem. Front. 7, 2335–2342 (2020).
Kiriya, D., Chang, H.-C. & Kitagawa, S. Molecule-based valence tautomeric bistability synchronized with a macroscopic crystal-melt phase transition. J. Am. Chem. Soc. 130, 5515–5522 (2008).
Lefter, C. et al. On the stability of spin crossover materials: from bulk samples to electronic devices. Polyhedron 102, 434–440 (2015).
Jayaraman, A., Bucher, E., Dernier, P. D. & Longinotti, L. D. Temperature-induced explosive first-order electronic phase transition in Gd-doped SmS. Phys. Rev. Lett. 31, 700–703 (1973).
Jayaraman, A. & Maines, R. G. Study of the valence transition in Eu-, Yb-, and Ca-substituted SmS under high pressure and some comments on other substitutions. Phys. Rev. B 19, 4154–4161 (1979).
Kahn, O. & Jay Martinez, C. Spin-transition polymers: from molecular materials toward memory devices. Science 279, 44–48 (1998).
Hay, M. A. & Boskovic, C. Lanthanoid complexes as molecular materials: the redox approach. Chem. Eur. J. 27, 3608–3637 (2021).
Walter, M. C., Booth, C. H., Lukes, W. W. & Andersen, R. A. Cerocene revisited: the electronic structure of and interconversion between Ce2(C8H8)3 and Ce(C8H8)2. Organometallics 28, 698–707 (2009).
Booth, C. W. et al. Intermediate-valence tautomerism in decamethylytterbocene complexes of methyl-substituted bipyridines. J. Am. Chem. Soc. 49, 17537–17549 (2010).
Sumino, Y., Harato, N., Tomisaka, Y. & Ogawa, A. A novel photoinduced reduction system of low-valent samarium species: reduction of organic halides and chalcogenides, and its application to carbonylation with carbon monoxide. Tetrahedron 59, 10499–10508 (2003).
CrysalisPro (Agilent Technologies, 2014).
Sheldrick, G. M. A short history of SHELX. Acta Crystallogr. A 64, 112–122 (2008).
Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr. C 71, 3–8 (2015).
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).
Degen, T., Sadki, M., Bron, E., König, U. & Nénert, G. The highscore suite. Powder Diffr. 29, S13–S18 (2014).
Neese, F. Software update: the ORCA program system, version 4.0. WIREs Comput. Mol. Sci. 8, e1327 (2018).
Pantazis, D. A. & Neese, F. All-electron scalar relativistic basis sets for the lanthanides. J. Chem. Theory Comput. 5, 2229–2238 (2009).
Rolfes, J. D., Neese, F. & Pantazis, D. A. All-electron scalar relativistic basis sets for the elements Rb–Xe. J. Comput. Chem. 41, 1842–1849 (2020).
Weigend, F. Accurate Coulomb-fitting basis sets for H to Rn. Phys. Chem. Chem. Phys. 8, 1057–1065 (2006).
Pantazis, D. A. & Neese, F. All-electron scalar relativistic basis sets for the 6p elements. Theor. Chem. Acc. 131, 1292 (2012).
Yamaguchi, K., Takahara, Y. & Fueno, T. in Applied Quantum Chemistry (eds Smith, V. H., Schaefer, H. F. & Morokuma, K.) 155–184 (D. Reidel, 1986).
Yamanaka, S., Kawakami, T., Nagao, H. & Yamaguchi, K. Effective exchange integrals for open-shell species by density functional methods. Chem. Phys. Lett. 231, 25–33 (1994).
Acknowledgements
K.S.P. thanks the VILLUM Foundation for a VILLUM Young Investigator+ (42094) grant, the Independent Research Fund Denmark for a DFF-Sapere Aude Starting grant (no. 0165-00073B) and the Carlsberg Foundation for a research infrastructure grant (no. CF17-0637). The X-ray spectroscopy experiments were performed at the ID12 beamline at the European Synchrotron Radiation Facility (Grenoble, France). We thank the Danish Agency for Science, Technology, and Innovation for funding the instrument centre Danscatt.
Author information
Authors and Affiliations
Contributions
K.S.P. and M.A.D. conceived and planned the research project. M.A.D., F.A. and A.S.M. developed and performed the synthesis and the crystallographic analysis. M.A.D., K.S.P. and J.B. performed the characterization of the magnetic properties. N.J.Y. and A.R. acquired and analysed the X-ray spectroscopic data. J.B. performed the DFT calculations. The manuscript was written by K.S.P. and M.A.D. with input from all coauthors. All authors have given their consent to the publication of the manuscript.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Chemistry thanks the anonymous reviewers 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. 1–13, Tables 1–4 and Discussion 1.
Supplementary Data 1
Crystallographic data for SmI2(pyz)3 at 230 K; CCDC reference 2285789.
Supplementary Data 2
Crystallographic data for SmI2(pyz)3 at 170 K; CCDC reference 2285788.
Supplementary Data 3
Crystallographic data for YbI2(pyz)3 at 230 K; CCDC reference 2300988.
Supplementary Data 4
Crystallographic data for YbI2(pyz)3 at 170 K; CCDC reference 2300987.
Supplementary Data 5
Crystallographic data for YbI2(pyz)3 at 120 K; CCDC reference 2285790.
Supplementary Data 5
Source Data for Supplementary Figs. 1, 2, 4, 5, 7 and 9–13.
Source data
Source Data Fig. 2
Source data for Fig. 2—magnetic data.
Source Data Fig. 3
Source data for Fig. 3—normalized XANES data.
Source Data Fig. 4
Source data for Fig. 4—magnetic data for solid solutions.
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.
About this article
Cite this article
Dunstan, M.A., Manvell, A.S., Yutronkie, N.J. et al. Tunable valence tautomerism in lanthanide–organic alloys. Nat. Chem. 16, 735–740 (2024). https://doi.org/10.1038/s41557-023-01422-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41557-023-01422-8
- Springer Nature Limited