Synthesis and crystal structure determination of Cs3Mg2P6O17N: The first example of a nitrido-oxo-cyclohexaphosphate

The synthesis of a new nitrido-oxo-phosphate, Cs3Mg2P6 O17N, has been perfo rmed by thermal ammonolysis of a mixture of CsPO3, MgO, and NH4H2PO4, and i ts crystal structure was determined from single-crystal data. The unit cell is cubic [space group Pa (3) over bar (Z = 4)] with a = 12.239(1) Angstrom . The structure consists of discrete cyclic arrangements of six P(O,N)(4) t etrahedra sharing two corners, thus forming large [P6O17N](7-) macroanions. These independent cyclic units are linked together through octahedrally co ordinated magnesium atoms, while cesium atoms occupy large cavities of the cyclohexaphosphate network and insure the electrical neutrality, Nitrogen a toms are randomly distributed with oxygen in a bridging P-(O,N)-P anionic p osition. Cs3Mg2P6O17N is a first term of a series of nitrogen-containing cy clohexaphosphates including the isotypic cesium oxynitrides Cs3Fe2P6O17N an d Cs3Co2P6O17N. (C) 2000 Academic Press.