Synthesis and Crystal Structure Determination of Cs3Mg2P6O17N: The First Example of a Nitrido-OxoCyclohexaphosphate

The synthesis of a new nitrido-oxo-phosphate, Cs3Mg2P6O17N, has been performed by thermal ammonolysis of a mixture of CsPO3, MgO, and NH4H2PO4, and its crystal structure was determined from single-crystal data. The unit cell is cubic [space group Pa (Z=4)] with a=12.239(1) ?. The structure consists of discrete cyclic arrangements of six P(O,N)4 tetrahedra sharing two corners, thus forming large [P6O17N]7- macroanions. These independent cyclic units are linked together through octahedrally coordinated magnesium atoms, while cesium atoms occupy large cavities of the cyclohexaphosphate network and insure the electrical neutrality. Nitrogen atoms are randomly distributed with oxygen in a bridging P-(O,N)-P anionic position. Cs3Mg2P6O17N is a first term of a series of nitrogen-containing cyclohexaphosphates including the isotypic cesium oxynitrides Cs3Fe2P6O17N and Cs3Co2P6O17N.