CaMg 2 P 6 O 3 N 10 – A Quinary Oxonitridophosphate with an Unprecedented Tetrahedra Network Structure Type

CaMg 2 P 6 O 3 N 10 has been synthesized starting from stoichiometric amounts of Ca(N 3 ) 2 , Mg 3 N 2 , P 3 N 5 , and PON in a high‐pressure/high‐temperature reaction at 8 GPa and 1100 °C. Adding small amounts of NH 4 Cl to the starting mixture afforded single crystals of CaMg 2 P 6 O 3 N 10 , which form transparent, colorless truncated octahedra. The crystal structure [space group I 4 1 / acd (no. 142), a = 12.494(1), c = 23.797(2) Å, Z = 16] was solved and refined by single‐crystal X‐ray diffraction analysis and confirmed by electron diffraction and transmission electron microscopy, including HRTEM image simulations. Rietveld refinement proved the phase purity of the product. FTIR analysis confirmed the absence N–H groups in the structure. Bond valence and lattice energy calculations (MAPLE) of the title compound are discussed. The crystal structure consists of polyhedral building units constructed from vertex‐sharing P(O,N) 4 tetrahedra with condensed dreier and sechser rings.