NA5RB[(WN3)(2)] AND NA5CS[(WN3)(2)], 2 NEW SODIUM NITRIDO TUNGSTATES(VI) WITH THE HEAVIER ALKALI-METALS RUBIDIUM AND CESIUM

Alkali metal amides react above 600 degrees C with tungsten powder in autoclaves to form nitrido tungstates(VI). Autoclaves are used for thi s type of reaction in order to avoid rapid decomposition of amides at relatively low temperatures to metal, nitrogen and hydrogen. Starting with an excess of the corresponding mixtures of amides the compounds N a5Rb[(WN3)(2)] and Na5Cs[(WN3)(2)] were obtained. After the reaction i s carried out the nitrido metallates(VI) are embedded in the alkali me tal. Orange-brown (Rb) and orange (Cs) crystals were isolated by extra cting the metals with liquid ammonia at room temperature. The structur es of the two compounds were determined by X-ray single crystal method s. Space group P2(1)/c (No. 14), Z = 8. Na5Rb[(WN3)(2)]: a = 9.355(2) Angstrom, b = 10.277(3) Angstrom, c = 19.165(3) Angstrom, beta = 90.12 (2)degrees. Na5Cs[(WN3)(2)]: a = 9.403(3) Angstrom, b = 10.236(2) Angs trom, c = 19.501(4) Angstrom, beta = 90.01(2)degrees. The isotypic com pounds contain infinite chains of corner sharing tetrahedra (1)(infini ty)[WN2N2/23-]. These chains are linked together three dimensionally b y sodium and the heavier alkali metal within each compound in a somewh at differing way.