Combining MN${}_6$ octahedra and PN${}_5$ trigonal bipyramids in the mica-like nitridophosphates MP${}_6$N${}_{11}$ (M=Al, In)

Layered silicates are a very versatile class of materials with high importance to humanity. The new nitridophosphates MP${}_6$N${}_{11}$ (M=Al, In), synthesized from MCl${}_3$, P${}_3$N${}_5$ and NH${}_4$N${}_3$ in a high-pressure high-temperature reaction at 1100 °C and 8 GPa, show a mica-like layer setup and feature rare nitrogen coordination motifs. The crystal structure of AlP${}_6$N${}_{11}$ was elucidated from synchrotron single-crystal diffraction data (space group Cm (no. 8), a=4.9354(10), b=8.1608(16), c=9.0401(18) Å, β=98.63(3)°), enabling Rietveld refinement of isotypic InP${}_6$N${}_{11}$. It is built up from layers of PN${}_4$ tetrahedra, PN${}_5$ trigonal bipyramids and MN${}_6$ octahedra. PN${}_5$ trigonal bipyramids have been reported only once and MN${}_6$ octahedra are sparsely found in the literature. AlP${}_6$N${}_{11}$ was further characterized by energy-dispersive X-ray (EDX), IR and NMR spectroscopy. Despite the vast amount of known layered silicates, there is no isostructural compound to MP${}_6$N${}_{11}$ as yet. (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH)