3d transition metal nitridophosphates MII P8 N14 (MII =Fe, Co, Ni) were prepared by high-pressure metathesis indicating that this route might give a systematic access to a structurally rich family of M-P-N compounds. Their structures, which are stable in air up to at least 1273 K, were determined through powder X-ray diffraction and consist of highly condensed tetra-layers of PN4 tetrahedra and MN6 octahedra. Magnetic measurements revealed paramagnetic behavior of CoP8 N14 and NiP8 N14 down to low temperatures while, FeP8 N14 exhibits an antiferromagnetic transition at TN =3.5(1) K. Curie-Weiss fits of the paramagnetic regime indicate that the transition metal cations are in a oxidation state +II, which was corroborated by Mössbauer spectroscopy for FeP8 N14 . The ligand field exerted by the nitride ions in CoP8 N14 and NiP8 N14 was determined from UV/Vis/NIR data and is comparable to that of aqua-ligands and oxophosphates.
Keywords: high-pressure chemistry; metathesis; nitrides; solid-state reactions; transition metals.
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