  We have prepared single crystals of WO3(4,4'-bipyridyl)0.5 and doped these by
Na-ion implantation. The structure of the resultant NaxWO3(4,4'-bipyridyl)0.5
was determined by single-crystal x-ray diffraction to comprise atomic layers of
corner-shared WO5N octahedra linked by the 4,4'-bypyridine via the apical
nitrogen. In the observed space group of Pbca, the fully ordered bipyridyl
molecules define cage-shaped structures, not the channels erroneously reported
previously for the Cmca polymorph. The Na ions are disordered bimodally about
the cage centre, displaced in the c-direction so as to lie closer to the apical
oxygens.
