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. 2026 Mar 4;148(11):11915–11924. doi: 10.1021/jacs.5c21756

Stabilization of the [C2N5]7– Anion in Recoverable High-Pressure Eu4Fe0.864(6)(C2N5)2 Pyronitridocarbonate

Fariia Iasmin Akbar †,*, Nityasagar Jena ‡,*, Christian Tobeck §, Pascal L Jurzick †, Niko T Flosbach §, Valerio Cerantola ∥, Elena Bykova ⊥, Lukas Brüning †, Andrey Aslandukov †, Dominik Spahr ⊥, Valentin Kovalev ⊥, Gaston Garbarino #, Anna Pakhomova #, Georgios Aprilis #, Nico Giordano 7, Leonid Dubrovinsky 8, Mathias S Wickleder §, Uwe Ruschewitz §, Igor A Abrikosov ‡, Maxim Bykov †,*
PMCID: PMC13022862  PMID: 41782174

Abstract

Synthesis at extreme conditions enables access to nitrogen-rich carbon–nitrogen anions that cannot be obtained at ambient conditions. Here, through a direct reaction between Eu­(N3)2 and EuC2 with Fe in a laser-heated diamond anvil cell (DAC) at 50(3) GPa, we synthesized the first inorganic hydrogen-free pyronitridocarbonate, Eu4Fe x (C2N5)2, x = 0.864(6), featuring novel highly charged [C2N5]7– anions, along with the first stoichiometric oxygen-free rare-earth metal guanidinate Eu5(CN3)3. The crystal structures of both compounds were determined via synchrotron single-crystal X-ray diffraction (SCXRD) and fully corroborated by density functional theory (DFT) calculations. Eu4Fe x (C2N5)2 was found to be recoverable at pressures close to ambient. Keeping the sample at ambient conditions for 1 day leads to splitting of half of the [C2N5]7– units in Eu4Fe x (C2N5)2 into the guanidinate [CN3]5– and carbodiimide [CN2]2– anions. The statistical analysis of the multigrain SCXRD data and DFT-based electronic structure analysis well defined the chemical nature of the bonding in [C2N5]7– and [CN3]5– anions. This study provides a clear synthetic pathway to a new class of inorganic nitridocarbonates.

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Introduction

Synthesis and stabilization of compounds containing complex nitridocarbonate anions is an emerging topic in high-pressure chemistry, offering access to previously unknown bonding motifs and highly charged carbon–nitrogen species. Carbon–nitrogen anions occur in important classes of inorganic solids and include widely studied cyanides [CN]−  and carbodiimides [CN2]2–, , as well as less common acetonitriletriides [C2N]3–, , dicyanamides [N­(CN)2]−, tricyanidomethanides [C­(CN)3]−, tetracyanoethylene radicals [C2(CN)4]•–, pentacyanoethanides [C2(CN)5]−, pentacyanopropenides [NCC­{C­(CN)2}2]−, , guanidinates [CN3]5–, tricyanidomelaminates [C6N9]3–, melonates [C6N7(NCN)3]3–, cyanopolyynides [C2n+1N]− (n = 0, 1, 2), cyano adduct anions of fullerenes [C60(CN) n ]− (n = 1, 3, 5), [C60(CN) n ]2– (n = 2, 4, 6), [C70(CN) n ]− (n = 1, 2, 3), and [C70(CN) n ]2– (n = 2, 4, 6). Ternary M–C–N compounds featuring nitrogen–nitrogen bonds are represented by the derivatives of tetrazole, e.g., 5-azidotetrazolate [CN7]−, 5,5′-azotetrazolate [N2(CN4)2]2–, , and 4,5-bis­(tetrazol-5-yl)-2H-1,2,3-triazolate [C2N3(CN4)2]3–.

Despite this structural diversity, most C–N anions remain nitrogen-poor. High-pressure synthesis is effective way to stabilize nitrogen-rich species, as was shown on the examples of various polynitrides. − Recent high-pressure reactions in multicomponent C–N systems yielded compounds featuring guanidinate [CN3]5–, , melaminate [C3N6]6–, , as well as the poly-N-(1,3,5-triazin-2-yl)-guanidine anions in Bi7C10N18(N3(1–x)O3x ). Syntheses at megabar pressure revealed the formation of polynitridocarbonates formed by anionic three-dimensional framework consisting of CN4 tetrahedra connected via di- or oligo-nitrogen linkers.

Despite recent discoveries in ternary C–N-containing compounds, many potential forms of C–N anions remain unknown. A similar tendency to form a wide variety of species composed of two light elements has been identified in high-pressure carbonates, where pressure stabilizes pyrocarbonates containing [C2O5]2– anions. − We hypothesize that by analogy with a series of carbonate-pyrocarbonate species, the elusive pyronitridocarbonate anion [C2N5]7– may also exist and be accessible in a high-pressure synthesis. The biggest challenge is to stabilize a relatively high odd-number charge in a rather small anion. Highly charged anions are typically found either in extended polyanionic frameworks (e.g., in Bi7C10N18(N3(1–x)O3x ), LaCN3 and CeCN5 ) or within large, isolated clusters ([P3N9]12– in Li12P3N9, [P4N10]10– in α-/β-Li10P4N10, and [B3P3N13]15– in Li47B3P14N42). Small highly charged isolated anions are rare. Among examples are the ethanide anions [C2]6– in Dy3C2. ,

In this work, we present the synthesis of the first inorganic hydrogen-free pyronitridocarbonate Eu4Fe0.864(6)(C2N5)2 featuring [C2N5]7– anionsfully deprotonated derivatives of biguanide C2N5H7. Under similar conditions we also obtained the first stoichiometric oxygen-free rare-earth element nitridocarbonate, Eu5(CN3)3.

Results and Discussion

We employed a new high-pressure synthetic strategy to access ternary and quaternary nitridocarbonates by laser-heating a mixture of europium azide Eu­(N3)2 and europium carbide EuC2 with a minor amount of iron in a DAC. Products of chemical reaction performed at 50(3) GPa and a temperature of 2800(200) K were identified by means of SCXRD at ESRF (ID15b, ID27) and DESY (P02.2) (see section Methods in the Supporting Information). The multigrain diffraction data analysis revealed the formation of several novel compounds in the laser-heated area. Full experimental details are provided in Tables S1–S6 and Figures S1–S4 of the Supporting Information. All supplemental results of the theoretical calculations are given in Tables S7–S10, Figures S5–S15, and Discussion S1. In the following sections, we describe the crystal structures and physical properties of two main products: Europium­(III) nitridocarbonate Eu5(CN3)3 and Europium­(III)–Iron­(II)-pyronitridocarbonate Eu4Fe0.864(6)(C2N5)2.

Europium Nitridocarbonate Eu5(CN3)3

Europium guanidinate Eu5(CN3)3 crystallizes in the monoclinic space group C2/c (Figure , Table S2) and contains three crystallographically unique Eu atoms (Eu1 and Eu2 occupying the 8f Wyckoff site, and Eu3 on the 4e site). The structure features two symmetry-independent guanidinate anions [CN3]5– with C–N distances varying in the range of ∼1.32–1.36 Å (Figure b), consistent with those reported for SbCN3, Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb), Sr4(Sr6N)2[In4]­[CN3]4, and (Sr9N1.33(8))­(SrIn3)­[CN3], supporting the formal C–N bond order of 1.33. Europium atoms are coordinated by 9 or 10 nitrogen atoms, forming a distorted monocapped tetragonal antiprism (Eu1), a cis-bicapped cube (Eu2), and a tricapped trigonal prism (Eu3) (Figure S2a). Eu5(CN3)3 remains detectable via synchrotron XRD down to 16(2) GPa during decompression (Table S3).

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Crystal structure of europium guanidinate Eu5(CN3)3 at 50(3) GPa. All Eu atoms are purple, C atoms are brown, and N atoms are blue; gray thin lines outline the unit cell. (a) The unit cell in projection along the b axis. (b) A view of the [CN3]5– units. (c) Charge density distribution in plains containing the [CN3]5– unit atoms. (d) Charge density isosurfaces of the guanidinate anions (with an isosurface level of 0.3).

The experimental crystal structure of Eu5(CN3)3 was fully optimized at 50 GPa within the GGA+U framework using both the PBE+U and PBEsol+U functionals. The optimized lattice parameters at 50 GPa exhibit excellent agreement with experimental values obtained from SCXRD data with a deviation of less than 2% (Table S8).

A BM3 EoS was used to describe volume–pressure dependence obtained from DFT calculations in the range of 0–60 GPa, yielding equilibrium unit cell volumes of 823 Å3 and 785 Å3 using PBE+U and PBEsol+U functionals, respectively, with an estimated bulk modulus K 0 in the range of 130–155 GPa (Figure a). Lattice parameters of Eu5(CN3)3 increase monotonically upon pressure release over the entire pressure range without any sign of lattice distortions (Figure S5a). Phonon dispersion relations calculated using the harmonic approximation (Figure S6) indicate dynamical instabilities in Eu5(CN3)3 both at the synthesis pressure and at 1 bar, attributed to C–N bond asymmetry in the [CN3]5– units. This instability is lifted by using finite-temperature phonon dispersion calculations at T = 300 K via the sTDEP method (Figure a, b).

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(a) The pressure dependence of the unit cell volume of Eu5(CN3)3 over a pressure range of 0–60 GPa, calculated using both PBE+U and PBEsol+U functionals within the DFT+U framework, compared with the experimental data. Solid lines correspond to the third-order Birch–Murnaghan Equation of State (BM3 EoS) based on DFT calculations. (b) The pressure dependence of the unit cell volume of Eu4Fe­(C2N5)2. The experimental data at ambient conditions for the Eu4Fe­(CN2)­(CN3)­(C2N5) is marked by different color (brown).

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(a)–(b) Finite temperature phonon dispersion relations and the phonon density of states (pDOS) for Eu5(CN3)3 at 50 GPa, and 1 bar, respectively, calculated using the sTDEP methods at T = 300 K. (c)–(d) Spin-resolved electronic density of states (eDOS) for Eu5(CN3)3 at 50 GPa and 1 bar, respectively, calculated using PBE+U functional.

Within the PBE+U calculations, at 50 GPa, Eu5(CN3)3 is an insulator with an energy gap between the occupied N 2p-states and unoccupied highly localized Eu 4f states of 1.39 eV for the spin-up channel and 2.27 eV for the spin-down channel (Figure c). Comparable bandgap values were obtained using the PBEsol+U functional (Table S8, Figures S7a and S8b). Eu5(CN3)3 remains insulating over the entire pressure range from 50 GPa to 1 bar (Figure c, d).

The occupied Eu 4f states lie at ∼6 eV below the Fermi energy, and nitrogen 2p orbitals dominate the valence band edge. The bandgap of Eu5(CN3)3 decreases monotonically upon decompression with an increasing discrepancy between PBE+U and PBEsol+U bandgap energy values (Figure S7a). Each europium atom in Eu5(CN3)3 carries a calculated magnetic moment of 6 μ B , with unoccupied localized 4f states near the conduction band edge comprising one f-electron from each europium atom.

Although the finite-temperature (T = 300 K) phonon dispersion relation calculated for Eu5(CN3)3 at ambient pressure shows the lattice dynamic stability of the compound (Figure b), it was not observed in our SCXRD experiments below a pressure of 16 GPa (Figure a).

Europium–Iron Pyronitridocarbonate Eu4Fe x (C2N5)2

Europium–iron pyronitridocarbonate, Eu4Fe x (C2N5)2, x = 0.864(6) (space group P21/c) (Table S4), contains an unprecedented pyronitridocarbonate [C2N5]7– anion (Figures and S3), representing the fully deprotonated form of biguanide C2N5H7. Europium, iron, nitrogen, and carbon atoms in Eu4Fe x (C2N5)2 occupy the following Wyckoff sites: 4e (Eu1, Eu2, N1–N5, C1, and C2) and 2a (Fe1) (Table S4). Two symmetry-independent Eu atoms, Eu1 and Eu2, are coordinated by 10 and 11 nitrogen atoms, respectively, forming a distorted bicapped tetragonal antiprism and a fully capped trigonal prism. Fe1 atoms feature octahedral coordination (Figure S2b).

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Crystal structure of europium pyronitridocarbonate Eu4Fe x (C2N5)2 at 50(3) GPa. Eu atoms are purple, Fe atoms are yellow, C atoms are brown, and N atoms are blue; gray thin lines outline the unit cell. (a) A general view of the crystal structure of Eu4Fe x (C2N5)2. (b) A pyronitridocarbonate anion geometry. (c) Charge density distribution in plains containing the [C2N5]7– unit atoms. (d) Charge density isosurface of the pyronitridocarbonate anion (with an isosurface level of 0.3).

The C–N distances in the [C2N5]7– units of Eu4Fe x (C2N5)2, determined at 50(3) GPa, are equal to ∼1.40–1.42 Å for bridging nitrogen atoms and ∼1.29–1.33 Å for the terminal nitrogen atoms (Figure b). Both distance ranges indicate an intermediate state between a single C–N bond (∼1.47 Å) and a bond of order 1.5, as observed in pyridine (d C–N ∼ 1.34 Å , ). Moreover, bond orders derived from the resonance forms of the biguanide molecule C2N5H7 are consistent with the C–N distances in the [C2N5]7– anions: 1.25 for the bridging atom and 1.375 for the terminal ones. The charge density distribution clearly shows the difference between the bridging and terminal C–N bonds in [C2N5]7– (Figure c, d), specifically, the peripheral bonds show a more pronounced electron density (Figure c, d). The geometry of the observed nonplanar [C2N5]7– anions (Figures b and S3) can be compared to those in pyrocarbonates, possessing a wide variety of anion geometries. −

The partial occupancy x = 0.864(6) of Fe in Eu4Fe x (C2N5)2, along with the interatomic C–N distances, was determined through the statistical analysis of 26 individual structure refinements (as described in the Methods section). The Mössbauer spectrum of Eu4Fe x (C2N5)2 at 50(3) GPa represents a singlet component with a center shift of 0.26 mm/s (Figure S4), in agreement with a low-spin state of Fe2+ in an octahedral coordination. , The low signal intensity is attributed to the fact that the sample was prepared with naturally occurring iron rather than 57Fe-enriched iron, which is typically used in high-pressure experiments exploiting Mössbauer spectroscopy as an analytical technique. The deviation from 100% Fe site occupancy requires the presence of a fraction of FeIII for the charge balance (e.g., Eu3FeII 0.592FeIII 0.272(C2N5)2). The FeIII component, regardless of its spin state, may lie below the detection limit of Mössbauer spectroscopy due to the low signal-to-noise ratio and overlap with the signal from the beamline optics and is therefore not clearly observable in the spectrum. Nonstoichiometry in iron-containing compounds, where iron is present predominantly in the +II oxidation state with a smaller proportion in the +III state, is well-known, as exemplified by wüstite Fe1–x O. ,

Decompression of the DAC containing the sample demonstrated the recoverability of Eu4Fe x (C2N5)2 down to ambient pressure (Tables S5 and S6). After ca. 1 day under ambient conditions, half of the [C2N5]7– anions split into guanidinate [CN3]5– and carbodiimide [CN2]2– anions (Figures b–d and S3), resulting in an abrupt increase of the unit cell volume and symmetry lowering (Table S6) in the compound, whose chemical formula can be written as Eu4Fe x (CN2)­(CN3)­(C2N5).

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Crystal structure of the europium pyronitridocarbonate after chemical transformation to Eu4Fe x (CN2)­(CN3)­(C2N5) under ambient conditions. Eu atoms are purple, Fe atoms are yellow, C atoms are brown, and N atoms are blue; gray thin lines outline the unit cell. (a) A general view of the crystal structure of Eu4Fe x (CN2)­(CN3)­(C2N5). (b) A view of the [C2N5]7– units before chemical transformation. (c) A view of the C–N anions after chemical transformation at ambient conditions. (d) Schematic representation of the [C2N5]7– anion splitting into guanidinate [CN3]5– and carbodiimide [CN2]2– anions.

The DFT+U optimized crystal structure of Eu4Fe­(C2N5)2 (space group P21/c) at 50 GPa shows excellent agreement with the experimental crystal structure obtained from SCXRD (Tables S4 and S9). In the DFT calculations, we used an idealized chemical composition with x = 1 for both Eu4Fe x (C2N5)2 and Eu4Fe x (CN2)­(CN3)­(C2N5). At ambient pressure, the calculated unit cell volume of Eu4Fe­(CN2)­(CN3)­(C2N5) differs from experiment by ∼5% with PBE+U, whereas PBEsol+U significantly improves the agreement with an error of less than 1.3% (Figure b, Table S9).

A BM3 fit to the pressure–volume data of Eu4Fe­(C2N5)2 yields an equilibrium unit cell volume of 426 Å3 and 406 Å3 using PBE+U and PBEsol+U, respectively (Figure b, with an estimated bulk modulus in the range of 90–100 GPa). The lattice parameters calculated within PBE+U closely match the experiment at 50 GPa, whereas PBEsol+U provides better agreement at ambient pressure. At 50 GPa, Eu4Fe­(C2N5)2 is dynamically stable as shown in Figure a. The experimental unit cell volumes at the intermediate pressure range 45–15 GPa fall between the PBE+U and PBEsol+U predictions (Figure b). Additionally, the lattice parameters (a, b, and c) of Eu4Fe­(C2N5)2 show a smooth, monotonous decrease over the pressure range 10–50 GPa (Figure S5b). Below 10 GPa, lattice distortions emerge, indicating potential phase transformations from Eu4Fe­(C2N5)2 to Eu4Fe­(CN2)­(CN3)­(C2N5). This interpretation is further supported by phonon dispersion calculations for Eu4Fe­(C2N5)2 at ambient pressure, which reveal imaginary phonon modes associated with Fe–N lattice vibrations, indicative of dynamic instability in Eu4Fe­(C2N5)2 (Figure S9). Conversely, the Eu4Fe­(CN2)­(CN3)­(C2N5) phase remains dynamically stable at ambient pressure (Figure b), supporting experimental observations.

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(a)–(b) Phonon dispersion relations and pDOS for Eu4Fe­(C2N5)2 at 50 GPa and Eu4Fe­(CN2)­(CN3)­(C2N5) at 1 bar using harmonic approximations. (c)–(d) Spin-resolved eDOS of Eu4Fe­(C2N5)2 at 50 GPa and Eu4Fe­(CN2)­(CN3)­(C2N5) at 1 bar calculated with the PBE+U and PBEsol+U functionals, respectively.

Figure c shows the spin-polarized total and partial eDOS of Eu4Fe­(C2N5)2 at 50 GPa, using the PBE+U functional. The phase exhibits an insulating behavior in both majority (spin-up) and minority (spin-down) spin channels, with energy gaps of 0.45 and 2.14 eV, respectively. The occupied Eu 4f states lie ∼ −6 eV below the Fermi level, while the unoccupied 4f states reside within the conduction band. Strong Fe 3d – N 2p hybridization occurs below the Fermi level for the spin-down channel, whereas in the spin-up channel the occupied Fe 3d states are distributed over a wider energy range of about 8 eV. The fundamental energy gap between the occupied (valence band) states and the unoccupied (conduction band) states is 0.45 eV, with unoccupied Eu 4f states exhibiting two distinct peaks, subject to a large exchange splitting induced by the localized moments of Eu 4f states with an energy width of 0.7 eV. A more detailed analysis of the eDOS and magnetic ordering for Eu4Fe­(C2N5)2 is provided in Supplementary Discussion S1.

Figure d shows the spin-polarized eDOS for Eu4Fe­(CN2)­(CN3)­(C2N5) at 1 bar, using PBEsol+U. It exhibits a band gap of 0.31 eV for the spin-up channel and 1.53 eV for the spin-down channel. In Eu4Fe­(CN2)­(CN3)­(C2N5), the occupied Eu 4f states appear at two distinct energy positions below the Fermi level: the majority of these states are positioned at −6 eV, while a smaller fraction appears just below the Fermi energy. A detailed analysis of the Wyckoff site resolved eDOS suggests that the Eu 4f states at −6 eV primarily originate from three europium sublattices (Eu1­(2a), Eu2­(2a), and Eu4­(2a)), whereas the occupied states just below the Fermi level arise from a single Eu3­(2a) sublattice (Figure S10d). This suggests a partial reduction of one Eu3+ ion to Eu2+ and oxidation of iron from +II to +III in Eu4Fe­(CN2)­(CN3)­(C2N5).

Conclusions

High-pressure synthesis at 50(3) GPa enabled the stabilization of fully deprotonated guanidinate [CN3]5– and pyronitridocarbonate [C2N5]7– anions in Eu5(CN3)3 and Eu4Fe x (C2N5)2 (x = 0.864(6)), respectively. The [C2N5]7– anion represents a key new member of the sp 2-hybridized C–N polyanion family, positioned between simple nitridocarbonates [CN3]5– and melaminates [C3N6]6– (Figure ). These results highlight the importance of precise pressure tuning and strategic selection of countercations for the design of highly charged nitridocarbonate species. While [CN3]5– can be stabilized by the group 5 and group 15 cations (e.g., Sb as shown experimentally for SbCN3, or V, Nb, Ta as predicted for (V,Nb,Ta)­CN3 ), stabilization of anions with the formal ionic charge of 7– is much more challenging and requires either a single element in a mixed-valence state, or a selected combination of two cations. In the case of [C2N5]7–, such stabilization was achieved by a combination of the Eu and Fe ions. This finding opens new directions for nitridocarbonate chemistry under extreme conditions.

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Schematic representation of the family of nitridocarbonates featuring progressive condensation of CN3 building blocks: [CN3]5–, ,, [C2N5]7–, [C3N6]6–, , and [C4N6 x–] n .

Traditional high-pressure routes to M–C–N phases often rely on metal–nitrogen reactions with carbon provided by the diamond anvils or involve C–N precursors such as cyanuric triazide (C3N12). ,, Our approach employs precursors that already contain oxidized metals with fixed M:C and M:N ratios, offering more opportunities for stoichiometry control.

Eu4Fe x (C2N5)2 significantly expands the chemistry of ternary and quaternary M–C–N compounds. Hitherto, only very few quaternary RE–Fe–C–N compounds had been explored, namely RE 2Fe17CN x (RE = Y, Sm, Gd, Tb, Dy, and Er) and NdFe­(CN)6. The former compounds are interstitial carbonitrides, while the latter is a cyanide. Among ternary rare earth-containing nitridocarbonate compounds, only carbodiimides RE 2(CN2)3 (RE = Sc, Sm, Yb, Lu , ), carbodiimide nitrides Ce3(CN2)3N, cyanamides EuCN2, and dicyanamides RE[N­(CN)2]3 (RE = La, Ce, Pr, Nd, Sm, Eu, and Gd) are known to date.

Finally, decompression of Eu4Fe x (C2N5)2 resulted in an interesting example of in crystallo chemistry: a single-crystal-to-single-crystal transformation in which 50% of the [C2N5]7– anions split into [CN2]2– and [CN3]5– anions while preserving the main structural motifs.

Supplementary Material

ja5c21756_si_001.docx (22.3MB, docx)

Acknowledgments

We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at P02.2 (PETRAIII). We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities under the proposal numbers CH-6885 (DOI: 10.15151/ESRF-ES-1685311408) and ES-1536 (DOI: 10.15151/ESRF-ES-1901553724).

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.5c21756.

  • Equations used in the statistical analysis of the C–N anions; crystallographic information; Synchrotron Mössbauer Source spectrum; supplementary DFT calculation results; supplementary discussion of theoretical computations (DOCX)

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

M.B. acknowledges the support of Deutsche Forschungsgemeinschaft (DFG Emmy-Noether project BY112/2–1). E.B. acknowledges the support of Deutsche Forschungsgemeinschaft (DFG Emmy-Noether project No. BY101/2–1). Co-funded by the European Union (ERC, HIPMAT, 101077963). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the EU or the ERC. N.J. and I.A.A. acknowledge support by the Knut and Alice Wallenberg Foundation (Wallenberg Scholar grant no. KAW-2018.0194 and KAW-2023.0309). Support from the Swedish Research Council (VR) grant no. 2023–05358 and the Swedish Government Strategic Research Areas in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU no. 2009 00971) is gratefully acknowledged. DFT calculations were enabled by high-performance computing (HPC) resources provided by the National Academic Infrastructure for Supercomputing in Sweden (NAISS) using Tetralith and Dardel at the National Supercomputer Center, Linköping University, partially funded by the Swedish Research Council through grant agreement no. 2022–06725. U.R. and C.T. acknowledge the support of Deutsche Forschungsgemeinschaft (project RU 546/15–1).

The authors declare no competing financial interest.

References

  1. Schulz A., Surkau J.. Main Group Cyanides: From Hydrogen Cyanide to Cyanido-Complexes. Rev. Inorg. Chem. 2023;43(1):49–188. doi: 10.1515/revic-2021-0044. [DOI] [Google Scholar]
  2. Sougrati M. T., Darwiche A., Liu X., Mahmoud A., Hermann R. P., Jouen S., Monconduit L., Dronskowski R., Stievano L.. Transition-Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium- and Sodium-Ion Batteries with Excellent Cycling Properties. Angew. Chemie - Int. Ed. 2016;55(16):5090–5095. doi: 10.1002/anie.201600098. [DOI] [PubMed] [Google Scholar]
  3. Corkett A. J., Reckeweg O., Pöttgen R., Dronskowski R.. The [NCN]2– Carbodiimide Complex Anion and Its Compounds–A “Divalent Nitride” Unit for Nitridocarbonates in Materials and Applications. Chem. Mater. 2024;36(19):9107–9125. doi: 10.1021/acs.chemmater.4c01615. [DOI] [Google Scholar]
  4. Jach F., Höhn P., Prots Y., Ruck M.. Sr4N­[CN2]­[C2N]: The First Carbodiimide Acetonitriletriide. Eur. J. Inorg. Chem. 2019;2019(9):1207–1211. doi: 10.1002/ejic.201801242. [DOI] [Google Scholar]
  5. Clark W. P., Köhn A., Niewa R.. The Quasi-Binary Acetonitriletriide Sr3[C2N]2 . Angew. Chem., Int. Ed. 2020;59(1):339–342. doi: 10.1002/anie.201912831. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Jürgens B., Irran E., Schnick W.. Synthesis and Characterization of the Rare-Earth Dicyanamides Ln[N­(CN)2]3 with Ln=La, Ce, Pr, Nd, Sm, and Eu. J. Solid State Chem. 2005;178(1):72–78. doi: 10.1016/j.jssc.2004.10.030. [DOI] [Google Scholar]
  7. Bessler K. E., Gatto C. C., Romualdo L. L., Ellena J. A., Sales M. J. de A.. Pseudohalides of Main Group Metals: The Alcaline Earth Tricyanomethanides - The Crystal Structures of Calcium and Barium Tricyanomethanide. Main Group Met. Chem. 2007;30(2–3):135–142. doi: 10.1515/MGMC.2007.30.2-3.135. [DOI] [Google Scholar]
  8. Her J.-H., Stephens P. W., Davidson R. A., Min K. S., Bagnato J. D., van Schooten K., Boehme C., Miller J. S.. Weak Ferromagnetic Ordering of the Li+[TCNE]•– (TCNE = Tetracyanoethylene) Organic Magnet with an Interpenetrating Diamondoid Structure. J. Am. Chem. Soc. 2013;135(48):18060–18063. doi: 10.1021/ja410818e. [DOI] [PubMed] [Google Scholar]
  9. Webster O. W.. Cyanocarbons: A Classic Example of Discovery-driven Research. J. Polym. Sci. A Polym. Chem. 2002;40(2):210–221. doi: 10.1002/pola.10087. [DOI] [Google Scholar]
  10. Hipps K. W., Geiser U., Mazur U., Willett R. D.. Cesium Pentacyanopropenide. Crystal Structure, Vibrational Spectra and Assignments, and Vibronic Structure in the Visible Emission Spectrum. J. Phys. Chem. 1984;88(12):2498–2504. doi: 10.1021/j150656a015. [DOI] [Google Scholar]
  11. Jäger L., Wagner C., Hanke W.. Crystal and Molecular Structure of Silver­(1,1,2,3,3-Pentacyanopropenide) J. Mol. Struct. 2000;525(1–3):107–111. doi: 10.1016/S0022-2860(00)00409-9. [DOI] [Google Scholar]
  12. Stelzer R. U., Wang Y., Dronskowski R., Niewa R.. (Sr9N1.33(8))­(SrIn3)­[CN3] and Sr4(Sr6N)2[In4]­[CN3]4: Two Fully Deprotonated Guanidinates Accessible from Pressureless Sodium Flux Synthesis. Inorg. Chem. 2025;64(14):6845–6856. doi: 10.1021/acs.inorgchem.4c05047. [DOI] [PubMed] [Google Scholar]
  13. Irran E., Jürgens B., Schnick W.. Trimerization of Alkali Dicyanamides M­[N­(CN)2] and Formation of Tricyanomelaminates M3[C6N9] (M = K, Rb) in the Melt: Crystal Structure Determination of Three Polymorphs of K­[N­(CN)2], Two of Rb­[N­(CN)2], and One of K3[C6N9] and Rb3[C6N9] from X-ray Powder Diffractometry. Chem. Eur. J. 2001;7(24):5372–5381. doi: 10.1002/1521-3765(20011217)7:24<5372::AID-CHEM5372>3.0.CO;2-#. [DOI] [PubMed] [Google Scholar]
  14. Horvath-Bordon E., Kroke E., Svoboda I., Fuess H., Riedel R.. Potassium Melonate, K3[C6N7(NCN)3]·5H2O, and Its Potential Use for the Synthesis of Graphite-like C3N4 Materials. New J. Chem. 2005;29(5):693–699. doi: 10.1039/b416390g. [DOI] [Google Scholar]
  15. Joalland B., Jamal-Eddine N., Kłos J., Lique F., Trolez Y., Guillemin J.-C., Carles S., Biennier L.. Low-Temperature Reactivity of C2n+1N– Anions with Polar Molecules. J. Phys. Chem. Lett. 2016;7(15):2957–2961. doi: 10.1021/acs.jpclett.6b01191. [DOI] [PubMed] [Google Scholar]
  16. Khairallah G., Peel J. B.. Cyano Adduct-Anions of [60]­Fullerene Observed by Electrospray Mass Spectrometry. Chem. Commun. 1997;60(3):253–254. doi: 10.1039/a607229a. [DOI] [Google Scholar]
  17. Khairallah G., Peel J. B.. Identification of Cyano Dianions of C60 by Electrospray Mass Spectrometry. Chem. Phys. Lett. 1997;268(3–4):218–222. doi: 10.1016/S0009-2614(97)00190-5. [DOI] [Google Scholar]
  18. Khairallah G., Peel J. B.. Cyano Adduct Anions of C70: Electrospray Mass Spectrometric Studies. J. Phys. Chem. A. 1997;101(36):6770–6774. doi: 10.1021/jp970635t. [DOI] [Google Scholar]
  19. Klapötke T. M., Stierstorfer J.. The CN7 – Anion. J. Am. Chem. Soc. 2009;131(3):1122–1134. doi: 10.1021/ja8077522. [DOI] [PubMed] [Google Scholar]
  20. Meng Y.. Poly­[μ-(5,5′-Diazenediylditetrazolido)-Dicaesium] Acta Crystallogr. 2011;E67:m453. doi: 10.1107/S1600536811008312. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Laus G., Kahlenberg V., Wurst K., Schottenberger H., Fischer N., Stierstorfer J., Klapötke T. M.. Synthesis and Crystal Structures of New 5,5′-Azotetrazolates. Crystals. 2012;2(1):127–136. doi: 10.3390/cryst2010127. [DOI] [Google Scholar]
  22. Luo L., Hao W., Jin B., Guo Z., Guo J., Liu Q., Deng H., Peng R.. Solvent-Free 3D Layered Energetic Metal Organic Framework: Structure, Stability, and Its Laser Response. J. Solid State Chem. 2023;317:123607. doi: 10.1016/j.jssc.2022.123607. [DOI] [Google Scholar]
  23. Laniel D., Winkler B., Koemets E., Fedotenko T., Bykov M., Bykova E., Dubrovinsky L., Dubrovinskaia N.. Synthesis of Magnesium-Nitrogen Salts of Polynitrogen Anions. Nat. Commun. 2019;10:4515. doi: 10.1038/s41467-019-12530-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Laniel D., Weck G., Gaiffe G., Garbarino G., Loubeyre P.. High-Pressure Synthesized Lithium Pentazolate Compound Metastable under Ambient Conditions. J. Phys. Chem. Lett. 2018;9(7):1600–1604. doi: 10.1021/acs.jpclett.8b00540. [DOI] [PubMed] [Google Scholar]
  25. Steele B. A., Stavrou E., Crowhurst J. C., Zaug J. M., Prakapenka V. B., Oleynik I. I.. High-Pressure Synthesis of a Pentazolate Salt. Chem. Mater. 2017;29(2):735–741. doi: 10.1021/acs.chemmater.6b04538. [DOI] [Google Scholar]
  26. Laniel D., Trybel F., Yin Y., Fedotenko T., Khandarkhaeva S., Aslandukov A., Aprilis G., Abrikosov A. I., Bin Masood T., Giacobbe C., Bright E. L., Glazyrin K., Hanfland M., Wright J., Hotz I., Abrikosov I. A., Dubrovinsky L., Dubrovinskaia N.. Aromatic Hexazine [N6]4– Anion Featured in the Complex Structure of the High-Pressure Potassium Nitrogen Compound K9N56 . Nat. Chem. 2023;15(5):641–646. doi: 10.1038/s41557-023-01148-7. [DOI] [PubMed] [Google Scholar]
  27. Wang Y., Bykov M., Chepkasov I., Samtsevich A., Bykova E., Zhang X., Jiang S., Greenberg E., Chariton S., Prakapenka V. B., Oganov A. R., Goncharov A. F.. Stabilization of Hexazine Rings in Potassium Polynitride at High Pressure. Nat. Chem. 2022;14(7):794–800. doi: 10.1038/s41557-022-00925-0. [DOI] [PubMed] [Google Scholar]
  28. Aslandukov A., Trybel F., Aslandukova A., Laniel D., Fedotenko T., Khandarkhaeva S., Aprilis G., Giacobbe C., Lawrence Bright E., Abrikosov I. A., Dubrovinsky L., Dubrovinskaia N.. Anionic N18 Macrocycles and a Polynitrogen Double Helix in Novel Yttrium Polynitrides YN6 and Y2N11 at 100 GPa. Angew. Chem., Int. Ed. 2022;61(34):e202207469. doi: 10.1002/anie.202207469. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Laniel D., Winkler B., Fedotenko T., Pakhomova A., Chariton S., Milman V., Prakapenka V., Dubrovinsky L., Dubrovinskaia N.. High-Pressure Polymeric Nitrogen Allotrope with the Black Phosphorus Structure. Phys. Rev. Lett. 2020;124(21):216001. doi: 10.1103/PhysRevLett.124.216001. [DOI] [PubMed] [Google Scholar]
  30. Aslandukov A., Aslandukova A., Laniel D., Khandarkhaeva S., Yin Y., Akbar F. I., Chariton S., Prakapenka V., Bright E. L., Giacobbe C., Wright J., Comboni D., Hanfland M., Dubrovinskaia N., Dubrovinsky L., Han M., Dubrovinskaia N., Dubrovinsky L.. Stabilization of N6 and N8 Anionic Units and 2D Polynitrogen Layers in High-Pressure Scandium Polynitrides. Nat. Commun. 2024;15(1):2244. doi: 10.1038/s41467-024-46313-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Brüning, L. ; Jena, N. ; Bykova, E. ; Jurzick, P. L. ; Flosbach, N. T. ; Mezouar, M. ; Hanfland, M. ; Giordano, N. ; Fedotenko, T. ; Winkler, B. ; Abrikosov, I. A. ; Bykov, M. . Stabilization of Guanidinate Anions [CN3]5– in Calcite-Type SbCN3 . Angew. Chem., Int. Ed. 2023, 62, e202311519 10.1002/anie.202311519. [DOI] [PubMed] [Google Scholar]
  32. Aslandukov A., Jurzick P. L., Bykov M., Aslandukova A., Chanyshev A., Laniel D., Yin Y., Akbar F. I., Khandarkhaeva S., Fedotenko T., Glazyrin K., Chariton S., Prakapenka V., Wilhelm F., Rogalev A., Comboni D., Hanfland M., Dubrovinskaia N., Dubrovinsky L.. Stabilization Of The CN3 5– Anion In Recoverable High-pressure Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates. Angew. Chem., Int. Ed. 2023;62(47):e202311516. doi: 10.1002/anie.202311516. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Ranieri U., Liang A., Lamb C., Spender J., Bolton S., Aslandukov A., Massani B., Tasnádi F., Autran P.-O., Ball J. A. D., Rosa A. D., Wang B., Trybel F., Laniel D.. High-Pressure Synthesis of Two Pb3(C3N6) Polymorphs Featuring Fully Deprotonated [C3N6]6– Melaminate Anions. J. Am. Chem. Soc. 2025;147(39):35431–35437. doi: 10.1021/jacs.5c09198. [DOI] [PubMed] [Google Scholar]
  34. Jurzick P. L., Brüning L., Winkler B., Wang Y., Dronskowski R., Bykova E., Spahr D., Hanfland M., Wehinger B., Giordano N., Bykov M.. Stabilization of Fully Deprotonated Melaminate Anions (C3N6)6– in M3(C3N6) (M = Cd, Ca) J. Am. Chem. Soc. 2026;148:2843. doi: 10.1021/jacs.5c16752. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Brüning, L. ; Jena, N. ; Jurzick, P. L. ; Bykova, E. ; Giordano, N. ; Mezouar, M. ; Abrikosov, I. A. ; Bykov, M. . High-Pressure Synthesis of Crystalline Double-Layer Carbon Nitride Networks Stabilized in Bi7C10N18(N3(1–x)O3x ). Angew. Chem., Int. Ed. 2025, 64, e202506406 10.1002/anie.202506406. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Aslandukov A., Liang A., Ehn A., Trybel F., Yin Y., Aslandukova A., Akbar F. I., Ranieri U., Spender J., Howie R. T., Bright E. L., Wright J., Hanfland M., Garbarino G., Mezouar M., Fedotenko T., Abrikosov I. A., Dubrovinskaia N., Dubrovinsky L., Laniel D.. Synthesis of LaCN3, TbCN3, CeCN5, and TbCN5 Polycarbonitrides at Megabar Pressures. J. Am. Chem. Soc. 2024;146(26):18161–18171. doi: 10.1021/jacs.4c06068. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Spahr D., Bayarjargal L., Bykov M., Brüning L., Jurzick P. L., Wang Y., Milman V., Refson K., Mezouar M., Winkler B.. Ca3[C2O5]2[CO3] Is a Pyrocarbonate Which Can Be Formed at p, T-Conditions Prevalent in the Earth’s Transition Zone. Commun. Chem. 2024;7(1):238. doi: 10.1038/s42004-024-01293-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Spahr D., Bayarjargal L., Bykov M., Brüning L., Reuter T. H., Milman V., Liermann H.-P., Winkler B.. High-Pressure Synthesis of Acentric Sodium Pyrocarbonate, Na2[C2O5] Dalton Trans. 2024;53(1):40–44. doi: 10.1039/D3DT03673A. [DOI] [PubMed] [Google Scholar]
  39. Spahr D., Bayarjargal L., Haussühl E., Luchitskaia R., Friedrich A., Milman V., Fedotenko T., Winkler B.. Twisted [C2O5]2–-Groups in Ba­[C2O5] Pyrocarbonate. Chem. Commun. 2023;59(80):11951–11954. doi: 10.1039/D3CC03324D. [DOI] [PubMed] [Google Scholar]
  40. Spahr D., König J., Bayarjargal L., Luchitskaia R., Milman V., Perlov A., Liermann H.-P., Winkler B.. Synthesis and Structure of Pb­[C2O5]: An Inorganic Pyrocarbonate Salt. Inorg. Chem. 2022;61(26):9855–9859. doi: 10.1021/acs.inorgchem.2c01507. [DOI] [PubMed] [Google Scholar]
  41. Spahr D., König J., Bayarjargal L., Milman V., Perlov A., Liermann H.-P., Winkler B.. Sr­[C2O5] Is an Inorganic Pyrocarbonate Salt with [C2O5]2– Complex Anions. J. Am. Chem. Soc. 2022;144(7):2899–2904. doi: 10.1021/jacs.2c00351. [DOI] [PubMed] [Google Scholar]
  42. Spahr D., Bayarjargal L., Bykov M., Brüning L., Jurzick P. L., Milman V., Giordano N., Mezouar M., Winkler B.. Synthesis and Characterization of Lithium Pyrocarbonate (Li2[C2O5]) and Lithium Hydrogen Pyrocarbonate (Li­[HC2O5]) Angew. Chem., Int. Ed. 2024;63(49):e202409822. doi: 10.1002/anie.202409822. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Bertschler E., Bräuniger T., Dietrich C., Janek J., Schnick W.. Li47B3P14N42A Lithium Nitridoborophosphate with [P3N9]12–, [P4N10]10–, and the Unprecedented [B3P3N13]15– Ion. Angew. Chem., Int. Ed. 2017;56(17):4806–4809. doi: 10.1002/anie.201701084. [DOI] [PubMed] [Google Scholar]
  44. Akbar F. I., Aslandukova A., Aslandukov A., Yin Y., Trybel F., Khandarkhaeva S., Fedotenko T., Laniel D., Bykov M., Bykova E., Dubrovinskaia N., Dubrovinsky L.. High-Pressure Synthesis of Dysprosium Carbides. Front. Chem. 2023;11:1210081. doi: 10.3389/fchem.2023.1210081. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Akbar F. I., Aslandukova A., Yin Y., Aslandukov A., Laniel D., Bykova E., Bykov M., Bright E. L., Wright J., Comboni D., Hanfland M., Dubrovinskaia N., Dubrovinsky L.. High-Pressure Dysprosium Carbides Containing Carbon Dimers, Trimers, Chains, and Ribbons. Carbon. 2024;228:119374. doi: 10.1016/j.carbon.2024.119374. [DOI] [Google Scholar]
  46. Bharatam P. V., Patel D. S., Iqbal P.. Pharmacophoric Features of Biguanide Derivatives: An Electronic and Structural Analysis. J. Med. Chem. 2005;48(24):7615–7622. doi: 10.1021/jm050602z. [DOI] [PubMed] [Google Scholar]
  47. Raczyńska E. D., Hallman M., Kolczyńska K., Stępniewski T. M.. On the Harmonic Oscillator Model of Electron Delocalization (HOMED) Index and Its Application to Heteroatomic π-Electron Systems. Symmetry. 2010;2(3):1485–1509. doi: 10.3390/sym2031485. [DOI] [Google Scholar]
  48. So̷rensen G. O., Mahler L., Rastrup-Andersen N.. Microwave Spectra of [15N] and [13C] Pyridines, Quadrupole Coupling Constants, Dipole Moment and Molecular Structure of Pyridine. J. Mol. Struct. 1974;20(1):119–126. doi: 10.1016/0022-2860(74)85074-X. [DOI] [Google Scholar]
  49. Eichhorn K.. Bond-Length–Bond-Strength Correlation between N–O and C–N of Pyridine N-Oxides. Acta Crystallogr. 1987;B43:111–112. doi: 10.1107/S0108768187098215. [DOI] [Google Scholar]
  50. Cerantola V., McCammon C., Kupenko I., Kantor I., Marini C., Wilke M., Ismailova L., Solopova N., Chumakov A., Pascarelli S., Dubrovinsky L.. High-Pressure Spectroscopic Study of Siderite (FeCO3) with a Focus on Spin Crossover. Am. Mineral. 2015;100(11–12):2670–2681. doi: 10.2138/am-2015-5319. [DOI] [Google Scholar]
  51. Gütlich, P. ; Bill, E. ; Trautwein, A. X. . Mössbauer Spectroscopy and Transition Metal Chemistry; Springer Berlin, Heidelberg, 2011. 10.1007/978-3-540-88428-6. [DOI] [Google Scholar]
  52. Gavarri J.-R., Carel C.. The Complex Nonstoichiometry of Wüstite Fe1‑zO: Review and Comments. Prog. Solid State Chem. 2019;53:27–49. doi: 10.1016/j.progsolidstchem.2018.10.001. [DOI] [Google Scholar]
  53. Liang Z., Li K., Zhang J., Conejo A. N.. Insights into Defect Cluster Formation in Non-Stoichiometric Wustite (Fe1–xO) at Elevated Temperatures: Accurate Force Field from Deep Learning. npj Comput. Mater. 2025;11(1):32. doi: 10.1038/s41524-025-01527-3. [DOI] [Google Scholar]
  54. Luo D., Qiao X., Dronskowski R.. Predicting Nitrogen-Based Families of Compounds: Transition-Metal Guanidinates TCN3 (T = V, Nb, Ta) and Ortho-Nitrido Carbonates T′2CN4 (T′=Ti, Zr, Hf) Angew. Chem., Int. Ed. 2021;60(1):486–492. doi: 10.1002/anie.202011196. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Yang Y., Pan Q., Zhang X., Ge S.. Magnetic Properties of R2Fe17CNX . J. Appl. Phys. 1992;72(7):2989–2992. doi: 10.1063/1.351506. [DOI] [Google Scholar]
  56. Jiao Y., Gao Q., Sanson A., Liang E., Sun Q., Chen J.. Understanding Large Negative Thermal Expansion of NdFe­(CN)6 through the Electronic Structure and Lattice Dynamics. Inorg. Chem. 2022;61(20):7813–7819. doi: 10.1021/acs.inorgchem.2c00310. [DOI] [PubMed] [Google Scholar]
  57. Kallenbach P., Ströbele M., Meyer H.. Missing Carbodiimide and Oxide Carbodiimide of Scandium: Sc2(CN2)3 and Sc2O2(CN2) Z. Anorg. Allg. Chem. 2020;646(15):1281–1284. doi: 10.1002/zaac.202000212. [DOI] [Google Scholar]
  58. Neukirch M., Tragl S., Meyer H.-J.. Syntheses and Structural Properties of Rare Earth Carbodiimides. Inorg. Chem. 2006;45(20):8188–8193. doi: 10.1021/ic0608952. [DOI] [PubMed] [Google Scholar]
  59. Reckeweg O., Schleid T., DiSalvo F. J.. Synthesis, Crystal Structure and Optical Spectra of Yb2[CN2]3 . Z. Naturforsch. 2007;62b(5):658–662. doi: 10.1515/znb-2007-0505. [DOI] [Google Scholar]
  60. Glaser J., Unverfehrt L., Bettentrup H., Heymann G., Huppertz H., Jüstel T., Meyer H.-J.. Crystal Structures, Phase-Transition, and Photoluminescence of Rare Earth Carbodiimides. Inorg. Chem. 2008;47(22):10455–10460. doi: 10.1021/ic800985k. [DOI] [PubMed] [Google Scholar]
  61. Unverfehrt L., Ströbele M., Glaser J., Meyer H.-J.. The Many Faces of Rare Earth Carbodiimide Compounds. Z. Anorg. Allg. Chem. 2009;635(12):1947–1952. doi: 10.1002/zaac.200900221. [DOI] [Google Scholar]
  62. Reckeweg O., DiSalvo F. J.. EuCN2  The First, but Not Quite Unexpected Ternary Rare Earth Metal Cyanamide. Z. Anorg. Allg. Chem. 2003;629(2):177–179. doi: 10.1002/zaac.200390025. [DOI] [Google Scholar]
  63. Nag A., Schnick W.. Synthesis, Crystal Structure and Thermal Behavior of Gadolinium Dicyanamide Dihydrate Gd­[N­(CN)2]3 · 2H2O. Z. Anorg. Allg. Chem. 2006;632(4):609–614. doi: 10.1002/zaac.200500479. [DOI] [Google Scholar]

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