Stabilization Of The CN₃⁵⁻ Anion In Recoverable High‐pressure Ln₃O₂(CN₃) (Ln=La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates

Abstract

A series of isostructural Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high‐pressure (25‐54 GPa) high‐temperature (2000‐3000 K) conditions in laser‐heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single‐crystal X‐ray diffraction (SCXRD) as well as corroborated by X‐ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln3O2(CN3) solids are composed of the hitherto unknown CN35‐ guanidinate anion — deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln3O2(CN3) (Ln = La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln3O2(CN3) compounds are recoverable to ambient conditions. The stabilization of the CN35‐ guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.

Trigonal Planar [PN3]4− Anion in the Nitridophosphate Oxide Ba3[PN3]O

“…The crystal structure was elucidated by scXRD data and confirmed by Rietveld refinement based on PXRD data. While a trigonal nitridic environment has already been reported for [BeN 3 ], [BN 3 ] and [CN 3 ] for the second period and for [ X N 3 ] ( X =Mn, Fe, Co, Ge] for the fourth period, we were able to close this gap with [PN 3 ] and detect the first representative of the third period [18,19,28,50–54] . This makes P the most versatile network‐forming cation of the main group nitrides and oxonitrides in terms of its coordination environment, as it can assume coordination numbers of three to six.…”

“…Recent reports detail the stabilization of a novel trigonal planar guanidinate (i.e. nitridocarbonate) anion, namely [CN 3 ] 5− , under high‐pressure [18,19] …”

Stabilization of Guanidinate Anions [CN3]5− in Calcite‐Type SbCN3

“…We can speculate that similar synthesis strategy and rational design may be applicable to the synthesis of orthonitridocarbonates [CN 4 ] 8À , analogous to orthocarbonates like M 2 CO 4 (M=Mg, Ca, Sr, Ba). [13][14][15] During the preparation and production of this manuscript we became aware of the similar synthesis of oxoguanidinates of f-block metals, [42] which demonstrates the universality of high-pressure approach for the preparation of novel nitridocarbonates.…”