Journal Article

PUBDB-2026-01759

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Stabilization of the [C$_2$N$_5$]$^{7-}$ Anion in Recoverable High-PressureEu$_4$Fe$_{0.864(6)}$(C$_2$N$_5$)$_5$)$_2$ Pyronitridocarbon

Akbar, F. I. (Corresponding author) ; Jena, N. (Corresponding author) ; Tobeck, C.Extern* ; Jurzick, P. L. ; Flosbach, N. T. ; Cerantola, V. ; Bykova, E.Extern* ; Brüning, L. ; Aslandukov, A. ; Spahr, D.Extern* ; Kovalev, V. ; Garbarino, G. ; Pakhomova, A. ; Aprilis, G.Extern* ; Giordano, N.DESY* ; Dubrovinsky, L. ; Wickleder, M. S. ; Ruschewitz, U. ; Abrikosov, I. A. ; Bykov, M. (Corresponding author)Extern*

2026
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/jacs.5c21756  doi:10.3204/PUBDB-2026-01759

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(N$_3$)$_2$ and EuC$_2$ with Fe in a laser-heated diamond anvil cell (DAC) at 50(3) GPa, we synthesized the first inorganic hydrogen-free pyronitridocarbonate, Eu$_4$Fex(C$_2$N$_5$)$_2$, x = 0.864(6), featuring novel highly charged [C$_2$N$_5$]$^{7-}$ anions, along with the first stoichiometric oxygen-free rare-earth metal guanidinate Eu$_5$(CN$_3$)$_3$. 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. Eu$_4$Fex(C$_2$N$_5$)$_2$ 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 [C$_2$N$_5$]$^{7-}$ units in Eu$_4$Fex(C$_2$N$_5$)$_2$ into the guanidinate [CN$_3$]$^{5-}$ and carbodiimide [CN$_2$]$^{2-}$ anions. The statistical analysis of the multigrain SCXRD data and DFT-based electronic structure analysis well defined the chemical nature of the bonding in [C$_2$N$_5$]$^{7-}$ and [CN$_3$]$^{5-}$ anions. This study provides a clear synthetic pathway to a new class of inorganic nitridocarbonates.

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Contributing Institute(s):

1. PETRA-D (FS-PETRA-D)
2. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. FS-Proposal: I-20240574 (I-20240574) (I-20240574)

Experiment(s):

1. PETRA Beamline P02.2 (PETRA III)

Appears in the scientific report 2026

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