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May 20, 2002
Volume 80, Number 20
CENEAR 80 20 p. 9
ISSN 0009-2347


Na3N synthesized from its elements by low-temperature technique


Sodium nitride, a compound that some scientists claimed could not exist, has been prepared and characterized by chemists at the Max Planck Institute for Solid-State Research, Stuttgart, Germany.

Research chemist Dieter Fischer and chemistry professor Martin Jansen prepared amorphous solid Na3N by generating atomic beams of sodium and nitrogen separately in a vacuum chamber and codepositing the atoms onto a liquid-nitrogen-cooled sapphire substrate [
Angew. Chem. Int. Ed., 41, 1755 (2002)].

The Na3N changes to a crystalline form when heated to room temperature and decomposes into its elements at 87 °C. Analysis of X-ray powder diffraction patterns of the crystals reveals that the compound has a lattice structure of the type known as anti-ReO3, in which octahedra are connected at all six corners to adjacent octahedra to form a three-dimensional network. Six sodium cations are located at the corners and one nitrogen atom is in the center of each octahedron.

"Sodium nitride is an extremely labile compound. It is impossible to prepare it using conventional solid-state reactions," Jansen tells C&EN. "Our approach can be used to carry out all solid-state reactions at unprecedented low temperatures."

The only other well-characterized alkali-metal nitride is Li3N, which forms spontaneously from lithium and nitrogen at room temperature. According to Rainer Niewa, a research chemist at the Max Planck Institute for Chemical Physics of Solids, Dresden, it might be feasible to use Fischer and Jansen's synthetic technique to prepare the binary nitrides of potassium, rubidium, and cesium.

"With the development of new synthetic routes, further new (especially metastable) compounds of nitrogen might be expected in the near future," Rainer suggests in the same issue of Angwandte Chemie (page 1701). "Such new compounds will inevitably have surprising structure chemistry and physical properties and, thus, provide new impulses in solid-state chemistry."


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Copyright © 2002 American Chemical Society

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