Structural characterization of quaternary selenites of tungsten(VI), WSeO ( = NH, Cs, Rb, K or Tl).

The quaternary WSeO ( = NH, Cs, Rb, K or Tl) selenites have been prepared in the form of single crystals by hydro-thermal and novel solid-state reactions. They were characterized by X-ray diffraction, thermal and spectroscopic studies. All of them have a hexa-gonal tungsten oxide (HTO) related [WSeO] anionic framework with pyramidally coordinated Se ions. The known WSeO ( = NH, Cs or Rb) compounds are isostructural with the CsWTeO compound and have a non-centrosymmetric layered structure containing intra-layer Se-O bonds. The new compound KWSeO(α) is isostructural with the KWTeO compound and has a centrosymmetric three-dimensional structure containing inter-layer Se-O bonds. It is inferred that the new TlWSeO compound has the same three-dimensional structure as KWSeO(α).