High‐Pressure Synthesis and Structural Investigation of H₃P₈O₈N₉: A New Phosphorus(V) Oxonitride Imide with an Interrupted Framework Structure

Abstract

The first crystalline phosphorus oxonitride imide H(3)P(8)O(8)N(9) (=P(8)O(8)N(6)(NH)(3)) has been synthesized under high-pressure and high-temperature conditions. To this end, a new, highly reactive phosphorus oxonitride imide precursor compound was prepared and treated at 12 GPa and 750 °C by using a multianvil assembly. H(3)P(8)O(8)N(9) was obtained as a colorless, microcrystalline solid. The crystal structure of H(3)P(8)O(8)N(9) was solved ab initio by powder X-ray diffraction analysis, applying the charge-flipping algorithm, and refined by the Rietveld method (C2/c (no. 15), a=1352.11(7), b=479.83(3), c=1820.42(9) pm, β=96.955(4)°, Z=4). H(3)P(8)O(8)N(9) exhibits a highly condensed (κ=0.47), 3D, but interrupted network that is composed of all-side vertex-sharing (Q(4)) and only threefold-linking (Q(3)) P(O,N)(4) tetrahedra in a Q(4)/Q(3) ratio of 3:1. The structure, which includes 4-ring assemblies as the smallest ring size, can be subdivided into alternating open-branched zweier double layers {oB,2(2)(∞)}[(2)P(3)(O,N)(7)] and layers containing pairwise-linked Q(3) tetrahedra parallel (001). Information on the hydrogen atoms in H(3)P(8)O(8)N(9) was obtained by 1D (1)H MAS, 2D homo- and heteronuclear (together with (31)P) correlation NMR spectroscopy, and a (1)H spin-diffusion experiment with a hard-pulse sequence designed for selective excitation of a single peak. Two hydrogen sites with a multiplicity ratio of 2:1 were identified and thus the formula of H(3)P(8)O(8)N(9) was unambiguously determined. The protons were assigned to Wyckoff positions 8f and 4e, the latter located within the Q(3) tetrahedra layers.

An Unprecedented AB2 Tetrahedra Network Structure Type in a High‐Pressure Phase of Phosphorus Oxonitride (PON)

“…The chemical shift of d iso = À32.1 ppm is close to those found for cristobalite-PON (d iso = À26.3 ppm, see spectrum in the Supporting Information) and H 3 P 8 O 8 N 9 (d iso = À31.9 ppm). [19] As expected for a phase with statistical O/N distribution, the full width at half maximum (FWHM) of the signal is so high that the four individual signals expected for the four crystallographically distinct P atoms cannot be resolved. To rule out the possibility of d-PON being in fact a phosphorus oxonitride imide, the absence of stoichiometric amounts of hydrogen was confirmed by 1 H solid-state NMR spectroscopy as well as FTIR spectroscopy.…”

Modular Principle for Complex Disordered Tetrahedral Frameworks in Quenched High‐Pressure Phases of Phosphorus Oxide Nitrides

“…High‐pressure high‐temperature treatment of amorphous phosphorus oxide nitride imide, obtained by ammonolysis of OP(NH 2 ) 3 , yielded a microcrystalline product whose powder diffraction pattern is somehow similar to that of H 3 P 8 O 8 N 9 , [35] but shows distinct differences on closer inspection. Small fragments were investigated by single‐crystal X‐ray diffraction (SCXRD) using microfocused synchrotron radiation at beamline 11 (ESRF, Grenoble).…”

“…P 40 O 31 N 46 (details are explained below), exhibits monoclinic metrics [ a =35.760(2) Å, b =4.7406(2) Å, c= 17.2016(13) Å, β =116.220(9)°, V=2616.0(3)Å 3 ], whereas P 74 O 59 N 84 exhibits a monoclinic lattice with similar a and b parameters but different c [ a =35.8371(17) Å, b =4.75039(17) Å, c= 30.0907(12) Å, β =107.755(5)°, V=4878.6(4) Å 3 ]. Both crystals are intergrown with a domain whose lattice parameters are similar to those of H 3 P 8 O 8 N 9 [35] . [ a =13.4993(19) Å, b =4.7399(6) Å, c =18.1395(20) Å, β =97.007(12)°, V=1153.0(2) Å 3 for the first and a =13.4942(20) Å, b =4.7518(4) Å, c =18.1588(12) Å, β =96.957(10)°, V =1155.8(2) Å for the second intergrown crystal].…”

“…Both crystals are intergrown with a domain whose lattice parameters are similar to those of H 3 P 8 O 8 N 9 . [35] [a = 13.4993 S3-S7. Energy-dispersive X-ray spectroscopy (EDX) showed no additional elements (Figure S6).…”

“…[32][33][34] Herein we present the phosphorus oxide nitrides P 40 O 31 N 46 and P 74 O 59 N 84 , which exhibit complex tetrahedral frameworks, and aim at relating the disorder in their structure to possible high-pressure phases. As both structures are related to that of H 3 P 8 O 8 N 9 , [35] with which the compounds are intergrown, the question of a modular building principle arises.…”